JP2021068594A - Induction heating device and induction heating method for rotating electric machine stator core - Google Patents

Abstract

To effectively heat tooth in an induction heating device for a rotating electric machine stator core.SOLUTION: An induction heating device 30 for a rotating electric machine stator core 10 includes: a columnar center core 31 which is arranged on the inner peripheral side of the rotating electric machine stator core 10 and around which an excitation coil 33 is wound; two end cores 35 arranged on both sides of the center core 31 in an axial direction and partially facing tooth 14 in the axial direction; a first heat insulation part 40 arranged between each end core 35 and the rotating electric machine stator core 10; and a second heat insulation part 42 arranged between the outer peripheral surface of the excitation coil 33 and the rotating electric machine stator core 10.SELECTED DRAWING: Figure 6

Description

The present disclosure relates to an induction heating device and an induction heating method for a rotary electric machine stator core, and particularly to efficiently heating teeth.

Conventionally, rotary electric machines such as motors and generators are configured by arranging a stator core and a rotor core so as to face each other in the radial direction. In the stator core, annealing may be performed in order to remove internal strain due to work hardening and reduce iron loss, which is a loss of the core. Since residual strain is generated in the stator core due to work hardening, especially in teeth, that portion may be annealed.

For example, a method is conceivable in which a high-frequency magnetic flux is applied to the entire stator core from one side in the axial direction, an in-plane eddy current is passed through the end portion of the stator core, and the Joule loss caused by the current is applied to heat the stator core.

Further, as in the configurations described in Patent Documents 1 and 2, a coil for inductive heating (induction heating unit) covers the entire outer periphery of the stator core in close proximity, and energizes the coil to apply an induced current to the stator core. A method of flowing and heating the stator core is known.

Further, as in the configuration described in Patent Document 3, the primary side yoke is passed through the inside of the coil, and the secondary side yoke magnetically coupled to the primary side yoke is passed through the central portion of the stator core to form a coil. A method is also known in which an alternating current is applied to the coil and an axial magnetic flux is passed through the stator core by the primary side yoke. According to this method, there is a possibility that an induced current can be passed through the stator core by the magnetic flux in the axial direction to heat the stator core.

JP 2013-5553 JP 2012-5283 JP-A-2018-81896

When a high-frequency magnetic flux is applied to the entire stator core from one side in the axial direction, the interlinking area of the magnetic flux in the stator core is large, so that the demagnetic field due to the eddy current becomes large and the reactive power becomes large. Further, in this case, a large amount of heat is generated except for the teeth that require annealing, so that the power consumption is large.

Further, in the methods described in Patent Documents 1 to 3, since the induced current flows only in the annular yoke portion on the outer peripheral portion of the stator core, only the yoke portion can be heated.

An object of the induction heating device and the induction heating method of the rotary electric machine stator core of the present disclosure is to efficiently heat the teeth.

The induction heating device for the rotary electric machine stator core of the present disclosure is an induction heating device for the rotary electric machine stator core including an annular yoke and a plurality of teeth extending radially inward from a plurality of positions in the circumferential direction of the yoke. A columnar central core arranged on the inner peripheral side of the stator core and wound with an exciting coil, and two end cores arranged on both sides of the central core in the axial direction and partially facing the teeth in the axial direction. A rotary electric machine including a first heat insulating portion arranged between the end core and the rotary electric machine stator core, and a second heat insulating portion arranged between the outer peripheral surface of the exciting coil and the rotary electric machine stator core. It is an induction heating device for the stator core.

The method of inducing heating of the rotary electric machine stator core of the present disclosure is a method of inducing heating the teeth of the rotary electric machine stator core by using the induction heating device of the rotary electric machine stator core of the present disclosure, and supplies an alternating current to the exciting coil. Thereby, the induction of the rotary electric machine stator core including the magnetic flux generation step in which a magnetic flux is passed through the central core and the teeth arranged between the two end cores and the two end cores to induce and heat the teeth. It is a heating method.

According to the induction heating device and the induction heating method of the rotary electric machine stator core of the present disclosure, the teeth can be heated efficiently.

It is a perspective view which shows the state which heats the rotary electric machine stator core by using the induction heating apparatus and the induction heating method of the rotary electric machine stator core of embodiment. It is a cut surface view which includes the central axis of the induction heating apparatus of FIG. FIG. 1 is an end view of the end core. It is a perspective view which shows by removing two end cores from FIG. It is an enlarged view of the part A of FIG. FIG. 2 is a diagram for explaining the reason why the teeth are heated intensively. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. FIG. 10 is a top view of FIG. It is a figure corresponding to FIG. 11 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 11 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a figure corresponding to FIG. 2 in the induction heating apparatus of another example of embodiment. It is a perspective view of the induction heating apparatus of another example of embodiment. FIG. 16 is a perspective view showing the two end cores removed. It is an end view of the end core in the induction heating apparatus of FIG. It is an end view of the end core in the induction heating apparatus of another example of embodiment. It is a figure which compared the Joule loss with respect to the frequency of the supply current to the exciting coil in a tooth and a yoke in the case of heating a rotary electric machine stator core by the induction heating device of an embodiment. When the rotary electric machine stator core is heated by the induction heating device of the embodiment, the Joule loss density (W / m ³ ) in a part of the circumferential direction of the rotary electric machine stator core when the thickness of the first heat insulating portion is small (1 mm). It is a figure which shows the analysis result of the distribution. When the rotary electric machine stator core is heated by the induction heating device of the embodiment, the Joule loss density (W / m ³ ) in a part of the circumferential direction of the rotary electric machine stator core when the thickness of the first heat insulating portion is large (5 mm). It is a figure which shows the analysis result of the distribution. ^{When the rotary electric machine stator core is heated by the induction heating device shown in FIG. 9, the Joule loss density (W / m 3} ) in a part of the circumferential direction of the rotary electric machine stator core when the thickness of the first heat insulating portion is large (set to 5 mm). It is a figure which shows the analysis result of the distribution of). ^{When the rotary electric machine stator core is heated by the induction heating device shown in FIG. 8A, the Joule loss density (W / m 3} ) in a part of the circumferential direction of the rotary electric machine stator core when the thickness of the first heat insulating portion is large (set to 5 mm). It is a figure which shows the analysis result of the distribution of).

Hereinafter, embodiments of an induction heating device and an induction heating method for a rotary electric machine stator core according to the present disclosure will be described in detail with reference to the drawings. In the following description, specific shapes, materials, numerical values, quantities, etc. are examples for facilitating the understanding of the present disclosure, and may be appropriately changed according to the specifications of the rotary electric machine stator core or the induction heating device. it can. In the following, similar elements will be described with the same reference numerals in all drawings.

FIG. 1 is a perspective view showing a state in which the rotary electric machine stator core 10 is heated by using the induction heating device 30 and the induction heating method of the rotary electric machine stator core 10 of the embodiment. FIG. 2 is a cut view including the central axis O of the induction heating device 30 of FIG. FIG. 3 is an end view of the end core 35 in FIG. FIG. 4 is a perspective view showing the two end cores 35 removed from FIG. FIG. 5 is an enlarged view of part A of FIG.

The rotary electric machine stator core 10 will be described with reference to FIGS. 1, 2, 4, and 5. Hereinafter, the rotary electric machine stator core 10 will be referred to as a stator core 10. The stator core 10 forms a stator together with a stator coil (not shown). The stator is used to form a rotary electric machine together with a rotor (not shown) located inside the stator.

The stator core 10 is an annular magnetic component, and is formed of a laminate formed by laminating annular electromagnetic steel plates such as a plurality of silicon steel plates in the axial direction (vertical direction in FIG. 1).

The stator core 10 includes a stator yoke 13 which is annularly arranged on the outer peripheral side, and a plurality of teeth 14 (FIGS. 2, 4, and 5) extending inward in the radial direction from a plurality of positions in the circumferential direction of the inner peripheral surface of the stator yoke 13. including. The plurality of teeth 14 are arranged at intervals in the circumferential direction. A slot 16 (FIG. 5), which is a groove, is formed between two adjacent teeth 14.

The stator coil has three phases of U, V, and W phases, and each coil is wound around a plurality of teeth 14 so as to straddle two slots 16 separated in the circumferential direction of the stator core 10.

When forming a rotary electric machine, the rotor is arranged inside the stator in the radial direction. The rotary electric machine is driven by supplying a three-phase alternating current to the three-phase stator coil during use. For example, a rotary electric machine is used as a permanent magnet type synchronous motor.

The stator core 10 is formed by laminating a plurality of electromagnetic steel sheets as described above, and the plurality of teeth 14 extend from the inner peripheral surface of the stator yoke 13. Each electrical steel sheet is formed into a predetermined shape by punching or the like. As a result, work hardening occurs in the teeth 14, and strain (residual strain) is likely to occur. Therefore, in the teeth 14, annealing is performed to remove internal strain and reduce iron loss.

For this reason, in the embodiment, an induction heating device 30 is used to anneal the stator core 10. The induction heating device 30 is arranged on the inner peripheral side of the stator core 10, and has a columnar central core 31 around which an exciting coil 33 (FIGS. 2, 4 and 5) is wound, two end cores 35, and two. The first heat insulating portion 40 (FIG. 2) and the second heat insulating portion 42 (FIG. 2) are included. In FIG. 2, the axial thickness of the end core 35 is made smaller in relation to the stator core 10 and the diameter of the central core 31 is made smaller in relation to the stator core 10 as compared with the shape shown in FIG. It shows a modified shape. Further, in FIG. 1, the illustration of the first heat insulating portion 40 and the second heat insulating portion 42 is omitted.

The central core 31 is made of a magnetic material and is formed, for example, in a columnar shape. The central core 31 is arranged along the central axis O on the central axis O of the stator core 10. Each of the two end cores 35 is a continuous mass made of a magnetic material and is formed in a disk shape. The two end cores 35 are arranged on both sides of the central core 31 in the axial direction. For example, the two end cores 35 are directly fixed so that their respective central axes O coincide with both axial end faces of the central core 31. At this time, one end core 35 and the center core 31 of the two end cores 35 are integrally formed, and after inserting the center core 31 on the inner peripheral side of the stator core 10, the other end core 35 of the two end cores 35 is inserted. The end core 35 and the center core 31 may be coupled. In addition, both end faces in the axial direction of the central core 31 and each end core 35 may be arranged so as to face each other apart in the axial direction via a gap.

With the end cores 35 arranged on both sides of the central core 31 in the axial direction, the outer peripheral side portion that is a part of each end core 35 faces the teeth 14 of the stator core 10 in the axial direction. Further, most of the portion of the stator yoke 13 is arranged outside in the radial direction (left-right direction in FIG. 2) from the outer peripheral surfaces of the two end cores 35.

For the central core 31, a powder core having high insulating properties such as a dust core or ferrite may be used. The central core 31 may be formed of an electromagnetic steel plate. At this time, the central core 31 may be a laminated core in which a plurality of electromagnetic steel sheets are laminated, one electromagnetic steel sheet may be spirally wound to form a cylindrical wound core, or a plurality of electrical steel sheets may be arranged radially in the radial direction. It may be used as a radial core.

If the cross-sectional shape when cut in a plane orthogonal to the central axis O of the central core is rectangular, the central core includes a plurality of elements divided in a direction parallel to one side such as a width direction, and a plurality of elements are included. It may be formed by binding. If the central core is cylindrical, the central core may be formed from a plurality of elements divided at a plurality of positions in the circumferential direction.

Since the end core 35 needs to be able to pass magnetic flux in both the axial direction and the radial direction, a powder core having high insulating properties such as a dust core or ferrite having isotropic magnetic characteristics is used. Is preferable. The end core 35 can also be formed of a plurality of electrical steel sheets, in which case it is preferable to use a radial core in which the plurality of electrical steel sheets are arranged radially in the radial direction.

Further, each first heat insulating portion 40 (FIG. 2) has a ring-shaped disk shape, and is on the outer peripheral side of the central core 31 the axial inner surface of the end core 35 and the axial direction of the plurality of teeth 14 of the stator core 10. It is placed between the end face. The first heat insulating portion 40 can be a block made of an insulating material having heat insulating properties such as resin or ceramic. The end core 35 and the stator core 10 may be brought into contact with the first heat insulating portion 40. The first heat insulating portion may be a gas having high heat insulating properties or an air layer instead of being a solid, and the induction heating device 30 and the stator core 10 are arranged in a vacuum state to form an end core 35. The vacuum gap formed between the stator core 10 and the stator core 10 may be used as the first heat insulating portion. By arranging the first heat insulating portion 40 between the axial inner surface of the end core 35 and the axial end surface of the stator core 10, heat escape from both axial ends of the teeth 14 is suppressed, and the teeth 14 Can be heated efficiently.

Further, the second heat insulating portion 42 has a cylindrical shape and is arranged between the outer peripheral surface of the exciting coil 33 and the inner peripheral surface of the stator core 10. The second heat insulating portion 42 may be made of an insulating material having heat insulating properties such as resin or ceramic, similarly to the first heat insulating portion 40. The inner peripheral surface of the stator core 10 and the outer peripheral surface of the exciting coil 33 may be brought into contact with the second heat insulating portion 42. The second heat insulating portion may be a gas having high heat insulating properties or an air layer instead of being a solid, and by arranging the induction heating device 30 and the stator core 10 in a vacuum state, the outer circumference of the exciting coil 33 may be formed. The vacuum gap formed between the surface and the inner peripheral surface of the stator core 10 may be used as the second heat insulating portion. By arranging the second heat insulating portion 42 between the outer peripheral surface of the exciting coil 33 and the inner peripheral surface of the stator core 10, it is possible to prevent the exciting coil 33 from being excessively heated by the radiant heat from the stator core 10. As a result, the exciting coil 33 can be protected and the performance deterioration of the exciting coil 33 can be suppressed.

In the method of inducing heating of the stator core 10 of the embodiment, a plurality of teeth 14 of the stator core 10 are induced and heated by using the above-mentioned induction heating device 30. At this time, as an arrangement step, as shown in FIGS. 1 and 2, the central core 31 around which the exciting coil 33 is wound is inserted on the inner peripheral side of the stator core 10, and two are inserted on both sides of the central core 31 in the axial direction. With the end core 35 arranged, the axial inner side surfaces of the end core 35 are opposed to both ends of the teeth 14 of the stator core 10 in the axial direction.

Then, as a magnetic flux generation step, by supplying an alternating current from the power supply unit (not shown) to the exciting coil 33, the central core 31 and the end core are in the direction of the solid line arrow α or the direction opposite to the solid line arrow α of FIG. A magnetic flux is passed through 35 and the teeth 14 of the stator core 10. The direction of the solid arrow α in FIG. 2 is the magnetic flux direction when the current flows on the front side of the paper surface in the right side portion of FIG. 2 of the exciting coil 33 and the current flows in the back side of the paper surface in the left side portion. As a result, the high-frequency magnetic flux flows in the axial direction of the teeth 14, and the teeth 14 are induced and heated to be annealed. At this time, the frequency of the alternating current flowing through the exciting coil 33 is set to a frequency (lower limit frequency) at which the skin thickness due to the eddy current due to the high frequency magnetic flux flowing through the stator core 10 is 1/3 or less of the circumferential width of the teeth 14. Is preferable. More preferably, the AC current frequency is a frequency (upper limit frequency) at which the skin thickness due to the eddy current due to the high frequency magnetic flux is equal to or larger than the plate thickness of the electromagnetic steel plate forming the stator core 10, and the circumferential width of the teeth 14. It is preferable that the frequency is 1/3 or less (lower limit frequency). As a result, a large amount of current can be passed through the teeth 14 that need to be heated and the root portion thereof in the stator core 10, so that the portion that particularly needs to be heated can be intensively heated due to Joule loss.

FIG. 6 is a diagram for explaining the reason why the teeth 14 are intensively heated in FIG. By supplying an alternating current to the exciting coil 33 as in FIG. 2, a high frequency magnetic flux flows in the axial direction of the teeth 14. At this time, when the exciting coil 33 is energized, a magnetic flux flows from the central core 31 to the end core 35 in the axial direction of the teeth 14 in the direction opposite to the solid line arrow α or the solid line arrow α in FIG. A part of the magnetomotive force of 33 generates an induced current in the circumferential direction of the stator yoke 13. Due to the induced current, a magnetic flux flowing around the stator yoke 13 is generated in the direction of the alternate long and short dash arrow β in FIG. This magnetic flux also flows to the teeth 14, and the magnetic flux direction at that time coincides with the magnetic flux direction of the solid arrow α. Therefore, it is easy to maintain a high magnetic flux density of the magnetic flux flowing in the tooth 14 in the axial direction, so that it is easy to maintain a high strength of the eddy current flowing inside the tooth 14, and the Joule loss of the eddy current is used to heat the tooth 14. Is promoted.

According to the induction heating device 30 and the induction heating method of the stator core 10, an alternating current is supplied to the exciting coil 33 wound around the central core 31 arranged on the inner peripheral side of the stator core 10 to obtain 2 A high-frequency magnetic flux flows through the teeth 14 arranged between the two end cores 35 to increase the Joule loss, thereby heating the teeth 14. As a result, the teeth 14 that require special heating are intensively heated, so that the teeth 14 can be efficiently heated. Therefore, the electric power required for heating the teeth 14 can be suppressed to a small extent, and the teeth 14 can be heated in a short time. Further, since it is possible to suppress that only the axial end portion of the teeth 14 is intensively heated, it is possible to prevent deterioration of magnetic characteristics due to overannealing.

FIG. 7 is a diagram corresponding to FIG. 2 in the induction heating device 30a of another example of the embodiment. In the case of the configuration of this example, each first heat insulating portion 40a is arranged so as to face not only the axial end surface of the teeth 14 but also the entire axial end surface of the stator core 10 including the teeth 14 and the stator yoke 13. ..

According to the above configuration, it is possible to suppress the escape of heat from the axial end surface of the stator yoke 13, so that the effect of heating the teeth 14 by increasing the temperature of the stator yoke 13 can be enhanced. In this example, other configurations and operations are the same as those of FIGS. 1 to 6.

FIG. 8A is a diagram corresponding to FIG. 2 in the induction heating device 30b of another example of the embodiment. In the case of the configuration of this example, in the induction heating device 30b, on the outer peripheral side of the two end cores 35, in the space on both end faces in the axial direction of the stator yoke 13, in the circumferential direction as a member corresponding to the auxiliary coil on the end face side. Two consecutive metal rings 44 are arranged. The metal ring 44 is formed of a highly conductive material such as copper, and is arranged so as to surround the end core 35 on the outer peripheral side of the end core 35. The cross section orthogonal to the circumferential direction of the metal ring 44 is rectangular, but the cross section may be another shape such as a circle.

According to the above configuration, it is possible to prevent the vicinity of the axial end surface of the stator yoke 13 from being excessively intensively heated, so that overannealing and deformation of the stator yoke 13 can be suppressed. Specifically, the inner surface of the end core 35 and the axial end surface of the stator core 10 are increased by increasing the thickness of the first heat insulating portion 40a between the inner surface of the end core 35 and the axial end surface of the stator core 10. The axial spacing between and may be relatively large. In this case, an alternating current flows through the exciting coil 33, so that a part of the magnetomotive force of the exciting coil 33 generates an induced current in the circumferential direction of the stator yoke. The circumferential direction of this induced current is opposite to the current direction of the exciting coil 33. Due to this induced current, a magnetic flux flowing around the stator yoke 13 is generated in the direction of the alternate long and short dash arrow β in FIG. 8A. Due to this magnetic flux, an eddy current increases near the axial end face of the stator yoke 13, and the axial end of the stator yoke 13 may be heated excessively intensively.

According to the configuration of this example, the induced current flows through the metal ring 44, so that, for example, a magnetic flux flowing around the metal ring 44 in the direction of the broken line arrow γ in FIG. 8A can be generated. Since the direction of the magnetic flux is opposite to the magnetic flux in the direction of the one-point chain line arrow β near the axial end face of the stator yoke 13, concentrated heating of the axial end portion of the stator yoke 13 by the magnetic flux is performed on the metal ring 44. It can be offset or relaxed by the magnetic flux due to the flowing induced current, and its concentrated heating can be suppressed. In this example, other configurations and operations are the same as those of FIGS. 1 to 6 or 7.

FIG. 8B is a diagram corresponding to FIG. 2 in the induction heating device 30c of another example of the embodiment. In the case of the configuration of this example, in the induction heating device 30c, on the outer peripheral side of the two end cores 35, in the space on both end faces in the axial direction of the stator yoke 13, as the end face side auxiliary coil, the winding start and winding end Two short-circuit coils 46 are arranged. The axial direction of the short-circuit coil 46 coincides with the axial direction of the exciting coil 33.

Also in the case of the above configuration, the induced current flows through the short-circuit coil 46 instead of the metal ring 44 having the configuration of FIG. 8A, so that a magnetic flux flowing around the short-circuit coil 46 can be generated, for example, in the direction of the broken arrow δ. .. Since the direction of the magnetic flux is opposite to the direction of the magnetic flux flowing near the axial end of the stator yoke 13 due to the induced current generated in the circumferential direction of the stator yoke 13, the axial end of the stator yoke 13 due to the magnetic flux Concentrated heating of the part can be suppressed. In this example, the other configurations and operations are the same as the configurations of FIGS. 1 to 6, the configuration of FIG. 7, or the configuration of FIG. 8A. The winding direction of the short-circuit coil 46 can be opposite to the winding direction of the exciting coil 33 as shown in FIG. 8B, but it may be the same direction as the exciting coil 33.

FIG. 8C is a diagram corresponding to FIG. 2 in the induction heating device 30d of another example of the embodiment. In the case of the configuration of this example, in the induction heating device 30d, on the outer peripheral side of the two end cores 35, in the space on both end faces in the axial direction of the stator yoke 13, as the end face side auxiliary coil, with respect to the exciting coil 33. Two end face side reverse polarity coils 48 connected so as to have opposite polarities are arranged. “Reverse polarity” means that the polarities of the two coils are opposite in the axial direction of the induction heating device 30d. The axial direction of the end face side reverse polarity coil 48 coincides with the axial direction of the exciting coil 33. For example, when the winding directions of the end face side reverse polarity coil 48 and the exciting coil 33 are reversed, the winding end end of the end face side reverse polarity coil 48 on one side in the axial direction (upper side in FIG. 8C) is wound around the exciting coil 33. It is connected to the start end, and the winding end end of the exciting coil 33 is connected to the winding start end of the end face side reverse polarity coil 48 on the other side in the axial direction (lower side in FIG. 8C). Further, the winding end end of the end face side reverse polarity coil 48 on the other side in the axial direction is connected to the winding start end of the end face side reverse polarity coil 48 on the other side in the axial direction via the power supply unit. The winding direction of the end face side reverse polarity coil may be the same as the winding direction of the exciting coil 33. At this time, the winding end end of the end face side reverse polarity coil on one side in the axial direction is connected to the winding end end of the exciting coil 33, and the winding start end of the exciting coil 33 is the winding start of the end face side reverse polarity coil on the other side in the axial direction. Connect to the end. Further, the winding end end of the end face side reverse polarity coil on the other side in the axial direction is connected to the winding start end of the end face side reverse polarity coil on the other side in the axial direction via the power supply unit.

In the case of the above configuration, the alternating current is supplied to the exciting coil 33, so that the alternating current also flows through the two end face side reverse polarity coils 48. At this time, for example, a magnetic flux flowing around the end face side reverse polarity coil 48 can be generated in the direction of the broken line arrow δ in FIG. 8C. Since the direction of the magnetic flux is opposite to the direction of the magnetic flux flowing near the axial end of the stator yoke 13 due to the induced current generated in the circumferential direction of the stator yoke 13, the axial end of the stator yoke 13 due to the magnetic flux. The concentrated heating can be offset or alleviated by the magnetic flux generated by the current flowing through the end face side reverse polarity coil 48, and the concentrated heating can be suppressed. In this example, the other configurations and operations are the same as the configurations of FIGS. 1 to 6, the configuration of FIG. 7, or the configuration of FIG. 8A.

In the configuration of FIG. 8C, the total number of turns (number of turns) of the two end face side reverse polarity coils 48 is preferably half or less of the number of turns of the exciting coil 33.

FIG. 9 is a diagram corresponding to FIG. 2 in the induction heating device 30e of another example of the embodiment. In the case of the configuration of this example, in the induction heating device 30e, the outer peripheral side is connected to the outer peripheral side of the stator yoke 13 with the number of turns less than half the number of turns of the exciting coil 33 and with the opposite polarity to the exciting coil 33. The polar coil 50 is arranged. “Reverse polarity” means that the polarities of the two coils are opposite in the axial direction of the induction heating device 30e. The axial direction of the outer peripheral side reverse polarity coil 50 coincides with the axial direction of the exciting coil 33. When the winding directions of the outer peripheral side reverse polarity coil 50 and the exciting coil 33 are matched, for example, the winding end end of one end side (lower side of FIG. 9) of the exciting coil 33 is set to one end side of the outer peripheral side reverse polarity coil 50. Connect to the end of winding (lower side of FIG. 9). Further, the winding start end of the other end side (upper side of FIG. 9) of the exciting coil 33 is connected to the winding start end of the other end side (upper side of FIG. 9) of the outer peripheral side reverse polarity coil 50 via the power supply unit. .. When the winding directions of the outer peripheral side reverse polarity coil 50 and the exciting coil 33 are reversed, for example, the winding end end on one end side (lower side of FIG. 9) of the exciting coil 33 is set on the outer peripheral side reverse polarity coil 50. Connect to the winding start end on the other end side (upper side in FIG. 9), and connect the winding start end on the other end side (upper side in FIG. 9) of the exciting coil 33 to one end of the outer peripheral side reverse polarity coil 50 via the power supply unit. Connect to the end of the winding on the side (lower side of FIG. 9).

Further, a cylindrical third heat insulating portion 52 is arranged between the inner peripheral surface of the outer peripheral side reverse polarity coil 50 and the outer peripheral surface of the stator core 10. The third heat insulating portion 52 has the same configuration as the second heat insulating portion 42, and has a larger diameter than the second heat insulating portion 42. Since the third heat insulating portion 52 can prevent the outer peripheral side reverse polarity coil 50 from being excessively heated by the radiant heat from the outer peripheral surface of the stator core 10, the outer peripheral side reverse polarity coil 50 can be protected and the outer peripheral side reverse polarity coil 50 can be protected. It is possible to suppress the performance deterioration of 50.

In the case of the above configuration as well, as in the configurations of FIGS. 8A to 8C, the deformation of the stator yoke 13 can be suppressed by preventing the axial end portion of the stator yoke 13 from being heated excessively intensively. Specifically, when it is assumed that there is no outer peripheral side reverse polarity coil 50, the axial distance between the inner surface of the end core 35 and the axial end surface of the stator core 10 is relatively large. Of the solid line arrows α in 9, as shown by the solid line arrows with X, the magnetic flux due to a part of the magnetomotive force of the exciting coil 33 spreads and flows in the stator yoke 13 due to the flow of the alternating current through the exciting coil 33. Then, the magnetic flux flowing in the vicinity of the axial end portion of the stator yoke 13 increases the eddy current in the vicinity of the axial end surface of the stator yoke 13. Therefore, the axial end portion of the stator yoke 13 may be heated excessively intensively. According to the configuration of this example, by supplying the alternating current to the exciting coil 33, the alternating current also flows to the outer peripheral side reverse polarity coil 50. At this time, for example, a magnetic flux flowing around the outer peripheral side reverse polarity coil 50 can be generated in the direction of the alternate long and short dash arrow η in FIG. Of the magnetic fluxes, the magnetic flux flowing as indicated by the one-point chain line arrow with X is the direction of the magnetic flux flowing near the axial end of the stator yoke 13 due to the magnetomotive force of the exciting coil 33 (the direction of the solid line arrow with X). Therefore, the concentrated heating of the axial end portion of the stator yoke 13 due to the magnetic flux can be offset or alleviated by the magnetic flux due to the current flowing through the outer peripheral side reverse polarity coil 50, and the concentrated heating can be suppressed. In this example, other configurations and operations are the same as those of FIGS. 1 to 6 or 7.

FIG. 10 is a diagram corresponding to FIG. 2 in the induction heating device 30f of another example of the embodiment. FIG. 11 is a top view of FIG. 10. In the case of the configuration of this example, in the same configuration as the induction heating device 30a of FIG. 7, the outer peripheral yoke 54 is arranged so as to cover the stator core 10, the central core 31, and the two end cores 35. As shown in FIG. 10, the outer peripheral yoke 54 has two plate portions 56 at both ends of the tubular portion 55 so as to close the openings at both ends of the tubular portion 55 so that the shape seen on the cut surface including the central axis is rectangular. Be connected. The tubular portion 55 has a cylindrical shape, and each plate portion 56 has a disk shape. The outer peripheral yoke 54 is connected to both ends in the axial direction of the central core 31 so that the inner side surfaces in the axial direction of the two plate portions 56 are in surface contact with each other. As a result, the outer peripheral yoke 54 is arranged so as to face the axially outer surfaces of the two end cores 35. In this state, a gap is formed between the inner peripheral surface of the tubular portion 55 of the outer peripheral yoke 54 and the outer peripheral surface of the stator core 10. The outer peripheral yoke 54 is made of a magnetic material. For example, as the outer peripheral yoke 54, a powder core having high insulating properties such as a dust core or ferrite may be used as in the central core 31. The outer peripheral yoke 54 may be formed of a laminated body of electromagnetic steel plates.

The outer peripheral yoke 54 can suppress the leakage flux from each end core 35 to the outside of the induction heating device 30f. A gap may be formed between the axially outer surface of at least one end core 35 of the two end cores 35 and the axial inner surface of the two plate 56s of the outer yoke 54. In this example, other configurations and operations are the same as those of FIGS. 1 to 6 or 7.

In the configuration of FIG. 10, the tubular portion of the outer peripheral yoke 54 may have a cylindrical shape, for example, a square tubular shape, or the like. For example, the outer peripheral yoke may be formed by a square tubular tubular portion and two square tubular portions.

FIG. 12 is a diagram corresponding to FIG. 11 in the induction heating device 30 g of another example of the embodiment. In the case of the configuration of this example, the outer peripheral yoke 54a is formed including the yoke element 57 having a rectangular cross section. The yoke element 57 has a rectangular frame shape in which two parallel rectangular plate portions 57b are connected to both ends in the longitudinal direction of the two parallel rectangular plate portions 57a. As a result, the cross-sectional shape cut at the center of the outer peripheral yoke 54 in the width direction (vertical direction in FIG. 12) becomes the same shape as in FIG. In the case of the induction heating device 30g using the outer peripheral yoke 54a, the leakage flux from each end core 35 to the outside of the induction heating device 30g can be suppressed in the same manner as in the configurations of FIGS. 10 and 11. In this example, other configurations and operations are the same as those of FIGS. 10 and 11.

FIG. 13 is a diagram corresponding to FIG. 11 in the induction heating device 30h of another example of the embodiment. In the case of the configuration of this example, there are two outer peripheral yokes 54b at the center in the longitudinal direction at both ends in the width direction (vertical direction in FIG. 13) of the first yoke element 58 having a shape similar to the shape of the outer peripheral yoke 54a in FIG. The gate-shaped second yoke element 59 is connected and formed. Each second yoke element 59 is connected to the longitudinal tip of two parallel rectangular plate portions 59a so that the rectangular connecting plate portion 59b is orthogonal to the plate portion 59a. As a result, the cross-sectional shape of the outer peripheral yoke 54b cut at the center of the first yoke element 58 in the width direction (vertical direction of FIG. 13) and the cross section of the second yoke element 59 cut at the center of the width direction (horizontal direction of FIG. 13). The shape is the same as that shown in FIG. As shown in FIG. 13, the shape of the outer peripheral yoke 54b viewed from one end in the axial direction is a cross shape. In the case of the induction heating device 30h using the outer peripheral yoke 54 as well, the leakage flux from each end core 35 to the outside of the induction heating device 30h is generated in the same manner as in the configuration of FIGS. 10 and 11 or 12. Can be suppressed. In this example, other configurations and operations are the same as those of FIGS. 10 and 11.

FIG. 14 is a diagram corresponding to FIG. 2 in the induction heating device 60 of another example of the embodiment. In the case of the configuration of this example, in the same configuration as in FIG. 8A, the outer peripheral yoke 54 covers the central core 31 and the two end cores 35 and has two ends, as in the configurations of FIGS. 10 and 11. The portion core 35 is arranged so as to face the outer surface in the axial direction. As a result, the action obtained by the configuration of this example is a combination of the action of the metal ring 44 of the configuration of FIG. 8A and the action of the outer peripheral yoke 54 of the configurations of FIGS. 10 and 11. In this example, the other configurations and operations are the same as those of FIG. 8A or the configurations of FIGS. 10 and 11. In the configuration of this example, instead of the configuration of FIG. 8A, the short-circuit coil 46 of the configuration of FIG. 8B or the end face side reverse polarity coil 48 of the configuration of FIG. 8C can be combined.

FIG. 15 is a diagram corresponding to FIG. 2 in the induction heating device 60a of another example of the embodiment. In the case of the configuration of this example, in the same configuration as in FIG. 9, the outer peripheral yoke 54 covers the central core 31 and the two end cores 35 and has two ends, as in the configurations of FIGS. 10 and 11. The portion core 35 is arranged so as to face the outer surface in the axial direction. As a result, the action obtained by the configuration of this example is a combination of the action of the outer peripheral side reverse polarity coil 50 of the configuration of FIG. 9 and the action of the outer peripheral yoke 54 of the configurations of FIGS. 10 and 11. In this example, the other configurations and operations are the same as those of FIG. 9 or the configurations of FIGS. 10 and 11.

In addition, in the configuration of FIG. 14 or the configuration of FIG. 15, instead of the configurations of FIGS. 10 and 11, the outer peripheral yokes 54a and 54b of the configuration of FIG. 12 or the configuration of FIG. 13 can be combined.

FIG. 16 is a perspective view of another example induction heating device 60b of the embodiment. FIG. 17 is a perspective view showing the two end cores 35a removed in FIG. FIG. 18 is an end view of the end core 35a in the induction heating device 60b of FIG. In the case of the configuration of this example, in the configuration of FIGS. 1 to 6, a hole 61 penetrating in the axial direction is formed in the central portion of the central core 31a and the two end cores 35a. At this time, each end core 35 is connected to both ends in the axial direction of the central core 31. A coolant pipe (not shown) is connected to the hole 61. A coolant such as oil or water is supplied to the upstream end of the hole 61 from a discharge port of a coolant pump (not shown) connected to the upstream side of the coolant pipe, and the coolant flows through the hole 61. The coolant discharged from the downstream end of the hole 61 is returned to the suction port of the coolant pump. As a result, the central core 31a is cooled. In this example, other configurations and operations are the same as those of FIGS. 1 to 6.

FIG. 19 is an end view of the end core 35b in another example induction heating device of the embodiment. In the configuration of this example, the end core 35b has a disk portion 62 having a hole 61 formed in the center portion and a radial plate portion 63 extending radially from a plurality of circumferential positions of the outer peripheral surface of the disk portion 62. It is formed by including. The disk portion 62 is connected to the axial end face of the central core 31. The number of radial plate portions 63 matches the number of teeth 14 (see FIG. 17) of the stator core 10. The plurality of radial plate portions 63 are arranged so as to face the axial end faces of the plurality of teeth 14. In this example, the other configurations and operations are the same as the configurations of FIGS. 1 to 6 or the configurations of FIGS. 16 to 18.

In addition, in the configuration of FIGS. 16 to 18 or the configuration of FIG. 19, a cooling member having higher thermal conductivity than the central core 31a and the end cores 35a and 35b instead of flowing the cooling liquid through the hole 61 (FIG. (Not shown) may be inserted into the hole 61. For example, the cooling member has a rod shape. The cooling member is formed of a metal having high thermal conductivity such as an aluminum alloy. The cooling member may be brought into contact with the inner surface of the hole 61. The portion of the cooling member protruding from the hole 61 may be connected to a cooling source (not shown) such as a heat sink. Even with such a configuration, the central core 31a can be cooled.

Note that the configuration of FIG. 19 may be such that no holes are formed in the end core 35b and the center core, as in the configurations of FIGS. 1 to 6.

Next, the analysis result performed for confirming the effect of the embodiment will be described. FIG. 20 compares the Joule loss with respect to the frequency of the supply current to the exciting coil 33 in the teeth 14 and the stator yoke 13 when the stator core 10 is heated by the induction heating device 30 of the embodiment shown in FIGS. 1 to 6. It is a figure.

As shown in FIG. 20, according to the embodiment, the Joule loss of the teeth 14 can be made significantly higher than that of the stator yoke 13 regardless of the difference in the frequency of the supply current to the exciting coil 33, so that the teeth 14 can be concentrated. It was confirmed that it could be heated.

21 to 24 show the analysis results of the distribution ^{of the Joule loss density (W / m 3} ) when the stator core 10 is heated by the induction heating device of the embodiment. FIG. 21 shows the circumference of the stator core 10 when the thickness of the first heat insulating portion 40 (FIG. 2) is small (1 mm) when the stator core 10 is heated by the induction heating device 30 of the embodiments of FIGS. 1 to 6. The analysis result of the distribution of Joule loss density in a part of the direction is shown. In FIG. 21, the portion of the stator core 10 having the lowest Joule loss density is shown as a plain portion. It is shown that the Joule loss density is higher in the order of the plain part, the sandy part, the diagonal line part, and the diagonal lattice part, and the Joule loss density is the highest in the black part.

From the analysis results of FIG. 21, it was confirmed that the teeth 14 can be heated intensively because the joule loss density of the teeth 14 can be increased and the joule loss density of the stator yoke 13 can be lowered according to the embodiment.

FIG. 22 shows the Joule loss density in a part of the circumferential direction of the stator core 10 when the thickness of the first heat insulating portion 40 (FIG. 2) is large (5 mm) when the stator core 10 is heated by the induction heating device of the embodiment. The analysis result of the distribution of is shown. In FIG. 22, the portion of the stator core 10 having the lowest Joule loss density is shown as a plain portion. Then, the joule loss density is higher in the order of the plain part, the sandy part, and the shaded part, and it is shown that the joule loss density is the highest in the black part.

From the analysis result of FIG. 22, when the thickness of the first heat insulating portion 40 is increased, the Joule loss density is higher near the end face of the stator yoke 13 than in the case of FIG. 21, and the temperature rise is likely to be large. confirmed. It is considered that the reason for this is that the axial end portion of the stator yoke 13 is likely to be heated intensively due to the leakage flux from the exciting coil 33.

On the other hand, FIG. 23 shows Joule loss in a part of the stator core 10 in the circumferential direction when the thickness of the first heat insulating portion 40a is large (5 mm) when the stator core 10 is heated by the induction heating device 30e shown in FIG. The analysis result of the density distribution is shown. In FIG. 23, the meanings of the plain portion, the sandy ground portion, the shaded portion, the diagonal grid portion, and the black background portion are the same as in the case of FIG. 21.

From the analysis result of FIG. 23, even when the thickness of the first heat insulating portion 40a was increased as in the case of FIG. 22, the Joule loss density was lower in the vicinity of the end face of the stator yoke 13 than in the case of FIG. 22. Therefore, when the induction heating device 30e is provided with the outer peripheral side reverse polarity coil 50 as in the configuration of FIG. 9, the axial end portion of the stator yoke 13 is concentrated due to the leakage flux from the exciting coil 33. It was confirmed that heating could be suppressed. Further, FIG. 24 shows Joule loss in a part of the stator core 10 in the circumferential direction when the thickness of the first heat insulating portion 40a is large (5 mm) when the stator core 10 is heated by the induction heating device 30b shown in FIG. 8A. The analysis result of the density distribution is shown. When the metal ring 44 was provided in the induction heating device as in the configuration of FIG. 8A, the result as shown in FIG. 24 was obtained. As a result, even when the thickness of the first heat insulating portion 40a is increased, the analysis result that the Joule loss density is low near the end surface of the stator yoke 13 is obtained. When the short-circuit coil 46 or the end face side reverse polarity coil 48 was provided in the induction heating device, the analysis result was the same as that shown in FIG. 24.

10 Rotating electric machine stator core (stator core), 13 stator yoke, 14 teeth, 16 slots, 30, 30a to 30h induction heating device, 31, 31a center core, 33 exciting coil, 35, 35a end core, 40, 40a first insulation Part, 42 2nd heat insulation part, 44 metal ring, 46 short circuit coil, 48 end face side reverse polarity coil, 50 outer circumference side reverse polarity coil, 52 3rd heat insulation part, 54, 54a, 54b outer circumference yoke, 55 cylinder part, 56 plates Part, 57 yoke element, 57a, 57b plate part, 58 first yoke element, 59 second yoke element, 60, 60a, 60b, 60c induction heating device, 61 holes, 62 disc part, 63 radial plate part.

Claims (6)

An induction heating device for a rotary electric machine stator core including an annular yoke and a plurality of teeth extending radially inward from a plurality of positions in the circumferential direction of the yoke.
A columnar central core arranged on the inner peripheral side of the rotary electric machine stator core and wound with an exciting coil, and
Two end cores that are arranged on both sides of the central core in the axial direction and partly face the teeth in the axial direction.
A first heat insulating portion arranged between the end core and the rotary electric machine stator core,
A second heat insulating portion arranged between the outer peripheral surface of the exciting coil and the rotary electric machine stator core is provided.
Induction heating device for rotary electric machine stator core. In the induction heating device for the rotary electric machine stator core according to claim 1.
On the outer peripheral side of the two end cores, in the space on both end faces in the axial direction of the yoke, a metal ring continuous in the circumferential direction, a short-circuit coil in which the start and end of winding are short-circuited, or the excitation coil. On the other hand, the end face side reverse polarity coil connected so as to have opposite polarity is arranged.
Induction heating device for rotary electric machine stator core. In the induction heating device for the rotary electric machine stator core according to claim 1.
On the outer peripheral side of the yoke, an outer peripheral side reverse polarity coil connected to the exciting coil with a reverse polarity with a number of turns less than half the number of turns of the exciting coil is arranged.
Induction heating device for rotary electric machine stator core. In the induction heating device for the rotary electric machine stator core according to any one of claims 1 to 3.
The central core and the two ends are formed by connecting two plates to both ends of the cylinder so as to close the openings at both ends of the cylinder, or by including a yoke element having a rectangular cross section. It covers the portion core and is arranged so as to face the axially outer surfaces of the two end cores.
Induction heating device for rotary electric machine stator core. In the induction heating device for the rotary electric machine stator core according to any one of claims 1 to 4.
A hole penetrating in the axial direction is formed in the central portion of the central core and the end core, and the cooling liquid flows through the hole, or for cooling having higher thermal conductivity than the central core and the end core. By inserting the member, the central core is cooled.
Induction heating device for rotary electric machine stator core. A method of inducing heating the teeth of the rotary electric machine stator core by using the induction heating device of the rotary electric machine stator core according to any one of claims 1 to 5.
By supplying an alternating current to the exciting coil, magnetic flux is passed through the central core and the teeth arranged between the two end cores and the two end cores, and magnetic flux is generated to induce and heat the teeth. Including steps,
Induction heating method for rotary electric machine stator core.

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