JP7184729B2 - Induction heating device and induction heating method for rotary electric machine stator core - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to an induction heating device and an induction heating method for a stator core of a rotating electrical machine, and more particularly to efficient heating of teeth.

2. Description of the Related Art Conventionally, rotary electric machines such as motors and generators are configured by arranging a stator core and a rotor core to face each other in the radial direction. Stator cores are sometimes annealed to remove internal strain due to work hardening and to reduce core loss. In the stator core, residual strain is generated due to work hardening, especially in the teeth, so that portion may be annealed.

For example, a high-frequency magnetic flux is applied to the entire stator core from one side in the axial direction, in-plane eddy currents are caused to flow through the ends of the stator core, and the resulting Joule loss is used to heat the stator core.

Further, as in the configurations described in Patent Documents 1 and 2, a coil (induction heating section) that performs induction heating closely covers the entire outer periphery of the stator core, and by energizing the coil, an induced current is generated in the stator core. It is known to flow and heat the stator core.

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 center of the stator core to It is also known to pass an alternating current through the primary yoke to cause an axial magnetic flux to flow inside the stator core. According to this method, it is possible that the stator core can be heated by causing an induced current to flow in the stator core due to this axial magnetic flux.

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

When high-frequency magnetic flux is applied to the entire stator core from one side in the axial direction, the magnetic flux interlinkage area in the stator core is large, so the demagnetizing field due to the eddy current increases, and the reactive power increases. Moreover, in this case, a large amount of heat is applied to parts other than the teeth that require annealing, resulting in large power consumption.

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 circumference of the stator core, only the yoke portion can be heated.

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

An induction heating apparatus for a rotating electric machine stator core of the present disclosure is an induction heating apparatus for a rotating 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, wherein the rotating electric machine a columnar center core disposed on the inner peripheral side of the stator core and wound with an excitation coil; two end cores disposed on both sides of the center core in the axial direction and partially facing the teeth in the axial direction; A rotating electrical machine comprising: a first heat insulating section arranged between the end core and the rotating electrical machine stator core; and a second heat insulating section arranged between the outer peripheral surface of the excitation coil and the rotating electrical machine stator core. It is an induction heating device for the stator core.

A rotary electric machine stator core induction heating method of the present disclosure is a method of induction heating the teeth of the rotary electric machine stator core using the rotary electric machine stator core induction heating apparatus of the present disclosure, wherein an alternating current is supplied to the excitation coil. Induction of a rotating electric machine stator core, including a magnetic flux generation step of inductively heating the teeth by causing the magnetic flux to flow through the central core and the two end cores and the teeth arranged between the two end cores. heating method.

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

1 is a perspective view showing a state in which a rotary electric machine stator core is heated using the rotary electric machine stator core induction heating device and the induction heating method of the embodiment; FIG. 2 is a cross-sectional view including the central axis of the induction heating device of FIG. 1; FIG. Figure 2 is an end view of the end core in Figure 1; Figure 2 is a perspective view of Figure 1 with two end cores removed; 5 is an enlarged view of part A in FIG. 4; FIG. FIG. 3 is a diagram for explaining the reason why the teeth are heated intensively in FIG. 2; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; It is the figure which looked at FIG. 10 from the top. FIG. 12 is a view corresponding to FIG. 11 in an induction heating device of another example of the embodiment; FIG. 12 is a view corresponding to FIG. 11 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; FIG. 3 is a view corresponding to FIG. 2 in an induction heating device of another example of the embodiment; It is a perspective view of the induction heating apparatus of another example of embodiment. FIG. 17 is a perspective view of FIG. 16 with two end cores removed; 17 is an end view of an end core in the induction heating apparatus of FIG. 16; FIG. It is an end view of an end core in an induction heating device of another example of an embodiment. FIG. 5 is a diagram comparing Joule loss with respect to frequency of current supplied to exciting coils in teeth and yokes when a rotating electric machine stator core is heated by the induction heating device of the embodiment. Joule loss density (W/m ³ ) in a part of the rotating electrical machine stator core in the circumferential direction when the thickness of the first heat insulating portion is small (1 mm) when the rotating electrical machine stator core is heated by the induction heating device of the embodiment. It is a figure which shows the analysis result of distribution. Joule loss density (W/m ³ ) in a part of the rotating electrical machine stator core in the circumferential direction when the thickness of the first heat insulating portion is large (5 mm) when the rotating electrical machine stator core is heated by the induction heating device of the embodiment. It is a figure which shows the analysis result of distribution. When the rotating electrical machine stator core is heated by the induction heating device shown in FIG. 9, the Joule loss density (W/m ³ ) is a diagram showing the analysis results of the distribution of . When the rotating electrical machine stator core is heated by the induction heating device shown in FIG. 8A , the Joule loss density (W/m ³ ) is a diagram showing the analysis results 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 understanding of the present disclosure, and can be changed as appropriate according to the specifications of the rotating electric machine stator core or the induction heating device. can. In the following description, similar elements are denoted by 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 using an induction heating device 30 and an induction heating method for the rotary electric machine stator core 10 of the embodiment. FIG. 2 is a cross-sectional view including the central axis O of the induction heating device 30 of FIG. FIG. 3 is an end view of end core 35 in FIG. FIG. 4 is a perspective view of FIG. 1 with two end cores 35 removed. FIG. 5 is an enlarged view of part A in FIG.

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

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

The stator core 10 includes a stator yoke 13 arranged in an annular shape on the outer peripheral side, and a plurality of teeth 14 (FIGS. 2, 4, and 5) extending radially inward from a plurality of circumferential positions on the inner peripheral surface of the stator yoke 13. including. A 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-phase coils 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 stator core 10 .

When constructing a rotating electric machine, a rotor is arranged radially inside a stator. A rotating electrical machine is driven by supplying a three-phase alternating current to a three-phase stator coil during use. For example, a rotating electric machine is used as a permanent magnet type synchronous motor.

Stator core 10 is configured by laminating a plurality of electromagnetic steel sheets as described above, and a plurality of teeth 14 extend from the inner peripheral surface of stator yoke 13 . Each electromagnetic 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. For this reason, the teeth 14 are annealed 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 includes a columnar central core 31 around which an exciting coil 33 (FIGS. 2, 4, and 5) is wound, two end cores 35, and two It includes a first heat insulating portion 40 (FIG. 2) and a second heat insulating portion 42 (FIG. 2). 2, compared to the shape shown in FIG. 1, the axial thickness of the end cores 35 is reduced in relation to the stator core 10, and the diameter of the center core 31 is reduced in relation to the stator core 10. It shows a modified shape. In addition, in FIG. 1, 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 has a cylindrical shape, for example. Central core 31 is arranged along central axis O of stator core 10 . Each of the two end cores 35 is a continuous lump of magnetic material and is formed in a disc shape. The two end cores 35 are arranged on both axial sides of the central core 31 . For example, the two end cores 35 are directly fixed so that their respective central axes O coincide with the axial end faces of the central core 31 . At this time, one end core 35 of the two end cores 35 and the center core 31 are integrally molded, and after the center core 31 is inserted into the inner peripheral side of the stator core 10, the other of the two end cores 35 is The end cores 35 and central core 31 may be joined together. Note that the axial end faces of the central core 31 and the respective end cores 35 may be axially spaced apart from each other to face each other.

With the end cores 35 arranged on both sides of the central core 31 in the axial direction, the outer peripheral side portions of the end cores 35 face the teeth 14 of the stator core 10 in the axial direction. Also, most of the stator yoke 13 is arranged radially outward (horizontal direction in FIG. 2) from the outer peripheral surfaces of the two end cores 35 .

A highly insulating powder core such as a dust core or ferrite may be used for the central core 31 . The central core 31 may be made of an electromagnetic steel sheet. At this time, the central core 31 may be a laminated core obtained by laminating a plurality of electromagnetic steel sheets, a cylindrical wound core obtained by spirally winding a single electromagnetic steel sheet, or a plurality of electromagnetic steel sheets arranged radially in the radial direction. It is good also as a radial core which carried out.

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

Since the end cores 35 need to allow passage of magnetic flux in both the axial direction and the radial direction, powder cores with high insulating properties such as dust cores and ferrite having isotropic magnetic properties are used. is preferred. The end core 35 can also be formed of a plurality of electromagnetic steel sheets, in which case it is preferable to form a radial core in which a plurality of electromagnetic steel sheets are radially arranged in the radial direction.

Further, each first heat insulating portion 40 ( FIG. 2 ) has a ring-shaped disc shape, and is arranged on the outer peripheral side of the center core 31 so as to extend axially from the inner side surface of the end core 35 and the plurality of teeth 14 of the stator core 10 in the axial direction. placed between the end faces. The first heat insulating part 40 can be a block made of an insulating material having heat insulating properties, such as resin or ceramic. The end cores 35 and the stator core 10 may be brought into contact with the first heat insulating portion 40 . It should be noted that the first heat insulating portion may not be solid, but may be gas having high heat insulating properties or an air layer. A vacuum gap formed between the stator core 10 and the stator core 10 may be used as the first heat insulating portion. By disposing 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 ends of the teeth 14 in the axial direction is suppressed, can be efficiently heated.

Further, the second heat insulating portion 42 is cylindrical and arranged between the outer peripheral surface of the exciting coil 33 and the inner peripheral surface of the stator core 10 . As with the first heat insulating portion 40, the second heat insulating portion 42 may be made of an insulating material having heat insulating properties, such as resin or ceramic. The inner peripheral surface of stator core 10 and the outer peripheral surface of exciting coil 33 may be brought into contact with second heat insulating portion 42 . It should be noted that the second heat insulating portion may be a gas having high heat insulating properties or an air layer instead of being solid. A 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 disposing 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 excitation coil 33 can be protected and performance degradation of the excitation coil 33 can be suppressed.

The induction heating method for the stator core 10 of the embodiment induction-heats the plurality of teeth 14 of the stator core 10 using the induction heating device 30 described above. At this time, first, as an arrangement step, as shown in FIGS. With the end cores 35 arranged, the axial inner side surfaces of the end cores 35 are opposed to the axial ends of the teeth 14 of the stator core 10 .

Then, as a magnetic flux generation step, by supplying an alternating current from a power source (not shown) to the excitation coil 33, the center core 31 and the end cores are moved in the direction of the solid line arrow α in FIG. 2 or in the direction opposite to the solid line arrow α. 35 and the teeth 14 of the stator core 10 . The direction of the solid-line arrow α in FIG. 2 is the magnetic flux direction when the current flows in the right side of FIG. As a result, high-frequency magnetic flux flows in the axial direction of the teeth 14, whereby the teeth 14 are induction-heated and annealed. At this time, the frequency of the alternating current flowing through the excitation coil 33 is set to a frequency (lower limit frequency) at which the skin thickness caused by eddy currents 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 preferred. More preferably, the alternating current frequency is a frequency (upper limit frequency) at which the skin thickness caused by eddy current due to the high-frequency magnetic flux is equal to or greater than the plate thickness of the electromagnetic steel sheet forming the stator core 10, and the circumferential width of the teeth 14 It is preferable that the frequency (lower limit frequency) is 1/3 or less. As a result, a large amount of electric current can be supplied to the teeth 14 and their root portions that need to be heated in the stator core 10, so that the portions that particularly need to be heated can be heated intensively by Joule loss.

FIG. 6 is a diagram for explaining why the teeth 14 are heated intensively in FIG. A high-frequency magnetic flux flows in the axial direction of the teeth 14 by supplying an alternating current to the excitation coil 33 as in FIG. At this time, when the excitation coil 33 is energized, magnetic flux flows in the axial direction of the teeth 14 from the central core 31 through the end cores 35 in the direction of the solid line arrow α in FIG. 6 or in the direction opposite to the solid line arrow α. Part of the magnetomotive force of 33 generates an induced current in the circumferential direction of the stator yoke 13 . The induced current generates a magnetic flux that flows around the stator yoke 13 in the direction of the dashed-dotted line arrow β in FIG. This magnetic flux also flows through the teeth 14, and the magnetic flux direction at that time coincides with the magnetic flux direction of the solid-line arrow α. Therefore, since the magnetic flux density of the magnetic flux flowing through the teeth 14 in the axial direction can be easily maintained high, the strength of the eddy current flowing inside the teeth 14 can be easily maintained high, and the Joule loss of the eddy currents can heat the teeth 14 . is promoted.

According to the induction heating device 30 and the induction heating method for the stator core 10 described above, 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, thereby A high-frequency magnetic flux flows through the teeth 14 arranged between the two end cores 35 to increase Joule loss, thereby heating the teeth 14 . As a result, the teeth 14 that particularly require heating are heated intensively, so that the teeth 14 can be efficiently heated. Therefore, the electric power required for heating the teeth 14 can be reduced, and the teeth 14 can be heated in a short time. In addition, since it is possible to suppress the concentrated heating of only the axial end portions of the teeth 14, it is possible to prevent deterioration of the magnetic properties due to over-annealing.

FIG. 7 is a diagram corresponding to FIG. 2 in an 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 to face not only the axial end face of the tooth 14 but also the entire axial end face of the stator core 10 including the tooth 14 and the stator yoke 13. .

According to the above configuration, heat escape from the axial end surface of the stator yoke 13 can be suppressed, so the temperature rise of the stator yoke 13 can increase the effect of heating the teeth 14 . Other configurations and actions in this example are the same as those in FIGS.

FIG. 8A is a diagram corresponding to FIG. 2 in an induction heating device 30b as 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 axial end faces of the stator yoke 13, in the circumferential direction as members corresponding to the end face side auxiliary coils. Two continuous metal rings 44 are arranged. The metal ring 44 is made of a highly conductive material such as copper, and is arranged on the outer peripheral side of the end core 35 so as to surround the end core 35 . Although the cross section perpendicular to the circumferential direction of the metal ring 44 is rectangular, the cross section may be circular or other shape.

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 and intensively heated, so that over-annealing and deformation of the stator yoke 13 can be suppressed. Specifically, by increasing the thickness of the first heat insulating portion 40 a between the inner surface of the end core 35 and the axial end surface of the stator core 10 , the inner surface of the end core 35 and the axial end surface of the stator core 10 can be separated from each other. may be relatively large in the axial direction. In this case, when an alternating current flows through the exciting coil 33, part of the magnetomotive force of the exciting coil 33 generates an induced current in the circumferential direction of the stator yoke. The direction of the induced current in the circumferential direction is opposite to the current direction of the exciting coil 33 . This induced current generates a magnetic flux that flows around the stator yoke 13 in the direction of the dashed-dotted arrow β in FIG. 8A. This magnetic flux may increase eddy currents near the axial end faces of the stator yoke 13 and cause excessive and concentrated heating of the axial ends of the stator yoke 13 .

According to the configuration of this example, it is possible to generate magnetic flux flowing around the metal ring 44 in the direction of the dashed arrow γ in FIG. Since the direction of the magnetic flux is opposite to the magnetic flux in the direction of the dashed-dotted arrow β near the axial end face of the stator yoke 13, the concentrated heating of the axial end of the stator yoke 13 by the magnetic flux is caused by the metal ring 44. It can be canceled or mitigated by the magnetic flux generated by the flowing induced current, and the concentrated heating can be suppressed. In this example, other configurations and actions are the same as the configuration in FIGS. 1 to 6 or the configuration in FIG.

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

In the above configuration as well, by causing the induced current to flow through the short-circuited coil 46 instead of the metal ring 44 in the configuration of FIG. . The direction of the magnetic flux is opposite to the direction of the magnetic flux flowing near the axial ends of the stator yoke 13 due to the induced current generated in the circumferential direction of the stator yoke 13. Concentrated heating of the part can be suppressed. In this example, other configurations and actions are similar to the configuration 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.

FIG. 8C is a diagram corresponding to FIG. 2 in an 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 above both axial end faces of the stator yoke 13, as an end face side auxiliary coil, for the exciting coil 33 Two end-side opposite-polarity coils 48 are arranged so that they are connected so that they have opposite polarities. "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 surface side reverse polarity coil 48 is made to coincide with the axial direction of the excitation coil 33 . For example, when the winding directions of the end face side reverse polarity coil 48 and the excitation coil 33 are reversed, the winding end of the end face side reverse polarity coil 48 on one side in the axial direction (upper side in FIG. 8C) is the winding end of the excitation coil 33. The winding end of the excitation coil 33 is connected to the winding start end of the end surface side opposite polarity coil 48 on the other side in the axial direction (lower side in FIG. 8C). In addition, the winding end of the end face side reversed polarity coil 48 on the other axial side is connected to the winding start end of the end face side reversed polarity coil 48 on the one side in the axial direction via the power supply section. The winding direction of the end surface side reverse polarity coil may be the same as the winding direction of the exciting coil 33 . At this time, the winding end of the end face side reverse polarity coil on one axial side is connected to the winding end end of the excitation coil 33, and the winding start end of the excitation coil 33 is connected to the winding start end of the end face side reverse polarity coil on the other axial side. connect to the ends. In addition, the winding end of the opposite-polarity coil on the other side in the axial direction is connected to the starting end of the opposite-polarity coil on the one side in the axial direction via the power supply unit.

In the case of the above configuration, alternating current is supplied to the exciting coil 33 , so that alternating current also flows through the two end face side opposite polarity coils 48 . At this time, for example, a magnetic flux can be generated that flows around the end surface side reverse polarity coil 48 in the direction of the dashed arrow δ in FIG. 8C. The direction of the magnetic flux is opposite to the direction of the magnetic flux flowing near the axial ends of the stator yoke 13 due to the induced current generated in the circumferential direction of the stator yoke 13. The concentrated heating can be canceled or mitigated by the magnetic flux generated by the current flowing through the end surface side reverse polarity coil 48, and the concentrated heating can be suppressed. In this example, other configurations and actions are similar to the configuration 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 of the two opposite polarity coils 48 is preferably half or less than the number of turns of the excitation coil 33 .

FIG. 9 is a diagram corresponding to FIG. 2 in an induction heating device 30e of another example of the embodiment. In the case of the configuration of this example, in the induction heating device 30 e , the outer peripheral side reverse coil 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 the polarity opposite to that of the exciting coil 33 . A polarizing 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 reverse polarity coil 50 coincides with the axial direction of the excitation coil 33 . When the winding directions of the outer circumference side reverse polarity coil 50 and the excitation coil 33 are matched, for example, the winding end of one end side (the lower side in FIG. 9) of the excitation coil 33 (lower side in FIG. 9). In addition, the winding start end of the other end side (upper side in FIG. 9) of the excitation coil 33 is connected to the winding start end of the other end side (upper side in FIG. 9) of the outer reverse polarity coil 50 via the power supply section. . When the winding directions of the outer circumference side reverse polarity coil 50 and the excitation coil 33 are reversed, for example, one end side (lower side in FIG. 9) of the excitation coil 33 is connected It connects to the winding start end on the other end side (upper side in FIG. 9), and the winding start end on the other end side (upper side in FIG. 9) of the exciting coil 33 is connected to one end of the outer peripheral reverse polarity coil 50 via the power supply unit. side (lower side in FIG. 9).

Furthermore, 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 reverse polarity coil 50 from being excessively heated by the radiant heat from the outer peripheral surface of the stator core 10, the outer reverse polarity coil 50 can be protected and the outer reverse polarity coil can be protected. 50 performance degradation can be suppressed.

8A to 8C, deformation of the stator yoke 13 can be suppressed by preventing the axial ends of the stator yoke 13 from being excessively and intensively heated. Specifically, assuming that the outer peripheral reverse polarity coil 50 does not exist, if the axial distance between the inner surface of the end core 35 and the axial end surface of the stator core 10 becomes relatively large, As shown by the solid line arrows with X attached to the solid line arrows α at 9 , magnetic flux due to part of the magnetomotive force of the exciting coils 33 spreads and flows through the stator yoke 13 when an alternating current flows through the exciting coils 33 . Eddy current increases near the axial end face of the stator yoke 13 due to the magnetic flux flowing near the axial end of the stator yoke 13 . Therefore, the axial ends of the stator yoke 13 may be heated excessively and in a concentrated manner. According to the configuration of this example, an alternating current flows through the outer-peripheral-side opposite-polarity coil 50 by supplying an alternating current to the excitation coil 33 . At this time, for example, a magnetic flux can be generated that flows around the outer-periphery-side opposite-polarity coil 50 in the direction of the dashed-dotted line arrow η in FIG. 9 . Among the magnetic fluxes, the magnetic flux flowing as indicated by the dashed-dotted 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 excitation coil 33 (the direction of the solid arrow with X). , the concentrated heating of the axial end portion of the stator yoke 13 due to the magnetic flux can be canceled or mitigated by the magnetic flux due to the current flowing through the reverse polarity coil 50 on the outer peripheral side, and the concentrated heating can be suppressed. In this example, other configurations and actions are the same as the configuration in FIGS. 1 to 6 or the configuration in FIG.

FIG. 10 is a diagram corresponding to FIG. 2 in an induction heating device 30f of another example of the embodiment. 11 is a top view of FIG. 10. FIG. In the case of the configuration of this example, the outer yoke 54 is arranged to cover the stator core 10, the center core 31 and the two end cores 35 in the same configuration as the induction heating device 30a of FIG. The outer yoke 54 has two plate portions 56 at both ends of the cylindrical portion 55 so as to close the openings at both ends of the cylindrical portion 55 so that the shape of the outer yoke 54 when viewed on a cross section including the central axis is rectangular as shown in FIG. concatenated. The cylindrical portion 55 is cylindrical, and each plate portion 56 is disk-shaped. The outer yoke 54 is connected to both ends of the central core 31 in the axial direction so that the inner side surfaces of the two plate portions 56 are in surface contact with each other. Thereby, the outer yoke 54 is arranged to face the axial outer surfaces of the two end cores 35 . In this state, a gap is formed between the inner peripheral surface of cylindrical portion 55 of outer yoke 54 and the outer peripheral surface of stator core 10 . The outer yoke 54 is made of a magnetic material. For example, for the outer yoke 54, similarly to the central core 31, a highly insulating powder core such as a dust core or ferrite may be used. The outer yoke 54 may be formed of a laminate of electromagnetic steel sheets.

The outer yoke 54 described above can suppress leakage magnetic flux from each end core 35 to the outside of the induction heating device 30f. A gap may be formed between the axial outer surface of at least one of the two end cores 35 and the axial inner surface of the two plate portions 56 of the outer yoke 54 . In this example, other configurations and actions are the same as the configuration in FIGS. 1 to 6 or the configuration in FIG.

In the configuration of FIG. 10, the cylindrical portion of the outer yoke 54 may have a shape other than a cylindrical shape, such as a square cylindrical shape. For example, the outer yoke may be formed by a square tube-shaped cylindrical portion and two square plate portions.

FIG. 12 is a diagram corresponding to FIG. 11 in an induction heating device 30g of another example of the embodiment. In the configuration of this example, the outer yoke 54a is formed including a yoke element 57 having a rectangular cross section. The yoke element 57 has a rectangular frame shape formed by connecting two parallel rectangular plate portions 57b to the longitudinal ends of two parallel rectangular plate portions 57a. As a result, the cross-sectional shape of the outer yoke 54 taken at the center in the width direction (vertical direction in FIG. 12) is similar to that shown in FIG. Also in the case of the induction heating device 30g using the outer peripheral yoke 54a, leakage magnetic flux from the end cores 35 to the outside of the induction heating device 30g can be suppressed as in the configuration of FIGS. Other configurations and actions in this example are the same as those in FIGS. 10 and 11 .

FIG. 13 is a diagram corresponding to FIG. 11 in an induction heating device 30h of another example of the embodiment. In the case of the configuration of this example, the outer yoke 54b has two yokes at the center in the longitudinal direction of both ends in the width direction (vertical direction in FIG. 13) of the first yoke element 58 having the same shape as the shape of the outer yoke 54a in FIG. A gate-shaped second yoke element 59 is connected and formed. Each second yoke element 59 is connected to the ends of two parallel rectangular plate portions 59a in the longitudinal direction so that a rectangular connecting plate portion 59b is perpendicular to the plate portions 59a. As a result, the cross-sectional shape of the outer yoke 54b taken at the center in the width direction (vertical direction in FIG. 13) of the first yoke element 58 and the cross-section taken at the center in the width direction (horizontal direction in FIG. 13) of the second yoke element 59 The shape is the same shape as in FIG. As shown in FIG. 13, the shape of the outer yoke 54b when viewed from one end in the axial direction is a cross. In the case of the induction heating device 30h using the outer peripheral yoke 54, similarly to the configuration of FIG. 10, FIG. 11, or the configuration of FIG. can be suppressed. Other configurations and actions in this example are the same as those in FIGS. 10 and 11 .

FIG. 14 is a diagram corresponding to FIG. 2 in an induction heating device 60 of another example of the embodiment. In the case of the configuration of this example, in a configuration similar to that of FIG. 8A, the outer yoke 54 covers the central core 31 and the two end cores 35, similar to the configurations of FIGS. It is arranged so as to face the axial outer surface of the partial core 35 . Thus, the effect obtained by the structure of this example is a combination of the effect of the metal ring 44 of the structure shown in FIG. 8A and the effect of the outer yoke 54 of the structure shown in FIGS. Other configurations and actions in this example are the same as the configuration in FIG. 8A or the configurations in FIGS. 10 and 11 . In addition, in the configuration of this example, instead of the configuration of FIG. 8A, the short-circuiting coil 46 of the configuration of FIG. 8B or the end surface side reverse polarity coil 48 of the configuration of FIG. 8C can be combined.

FIG. 15 is a diagram corresponding to FIG. 2 in an induction heating device 60a of another example of the embodiment. In the case of the configuration of this example, in a configuration similar to that of FIG. 9, the outer yoke 54 covers the central core 31 and the two end cores 35, as in the configurations of FIGS. It is arranged so as to face the axial outer surface of the partial core 35 . Thus, the effect obtained by the configuration of this example is a combination of the effect of the outer reverse polarity coil 50 of the configuration of FIG. 9 and the effect of the outer yoke 54 of the configuration of FIGS. Other configurations and actions in this example are the same as those of the configuration of FIG. 9 or the configurations of FIGS.

14 or 15, the outer yokes 54a and 54b having the configuration shown in FIG. 12 or 13 can be combined instead of the configurations shown in FIGS.

FIG. 16 is a perspective view of an induction heating device 60b as another example of the embodiment. FIG. 17 is a perspective view of FIG. 16 with two end cores 35a removed. 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 is formed through the central portion of the central core 31a and the two end cores 35a in the axial direction. At this time, each end core 35 is connected to both axial ends of the center 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 . Coolant discharged from the downstream end of hole 61 is returned to the inlet of the coolant pump. This cools the central core 31a. Other configurations and actions in this example are the same as those in FIGS.

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

16 to 18 or the configuration of FIG. 19, instead of circulating the coolant through the holes 61, a cooling member having higher thermal conductivity than the central core 31a and the end cores 35a and 35b (not shown) may be inserted into hole 61 . For example, the cooling member is rod-shaped. The cooling member is made of, for example, metal with high thermal conductivity such as aluminum alloy. A 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. Such a configuration can also cool the central core 31a.

19, the end cores 35b and the central core may be configured without holes, as in the configurations of FIGS. 1 to 6. FIG.

Next, the results of analysis performed to confirm the effects of the embodiment will be described. FIG. 20 compares the Joule loss with respect to the frequency of the current supplied 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. It is a diagram.

As shown in FIG. 20, according to the embodiment, the joule loss of the teeth 14 can be significantly higher than that of the stator yoke 13 regardless of the difference in the frequency of the current supplied to the exciting coil 33. I was able to confirm that it can be heated.

21 to 24 show analysis results of distribution of Joule loss density (W/m ³ ) when 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 embodiment of FIGS. It shows the analysis results of the distribution of Joule loss density in a part of directions. In FIG. 21 , the portion with the lowest Joule loss density in the stator core 10 is indicated by the non-coated portion. The joule loss density increases in the order of the non-coated portion, the sandy portion, the hatched portion, and the slanted lattice portion, and the joule loss density is highest in the black portion.

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

FIG. 22 shows the Joule loss density in a part of the stator core 10 in the circumferential direction 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. shows the analysis results of the distribution of In FIG. 22 , the portion with the lowest Joule loss density in the stator core 10 is indicated by the non-coated portion. The Joule loss density increases in the order of the non-coated portion, the sandy portion, and the hatched portion, and the Joule loss density is highest in the black portion.

From the analysis results of FIG. 22, when the thickness of the first heat insulating portion 40 is increased, the Joule loss density near the end surface of the stator yoke 13 becomes higher than in the case of FIG. confirmed. A possible reason for this is that the axial ends of the stator yoke 13 tend to be heated in a concentrated manner due to the leakage magnetic flux from the exciting coil 33 .

On the other hand, FIG. 23 shows the 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. 4 shows analysis results of density distribution. In FIG. 23, the non-patterned portion, the sanded portion, the hatched portion, the slanted grid portion, and the black portion have the same meanings as in FIG.

From the analysis result of FIG. 23, even when the thickness of the first heat insulating portion 40a is increased as in the case of FIG. 22, the Joule loss density near the end face of the stator yoke 13 is lower than in the case of FIG. For this reason, when the induction heating device 30e is provided with the reverse polarity coil 50 on the outer peripheral side as in the configuration of FIG. It was confirmed that heating could be suppressed. 24 shows the 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. 4 shows analysis results of density distribution. When the induction heating device was provided with the metal ring 44 as in the configuration of FIG. 8A, the results shown in FIG. 24 were obtained. As a result, even when the thickness of the first heat insulating portion 40a is increased, an analysis result is obtained in which the Joule loss density is low near the end surface of the stator yoke 13 . When the induction heating device was provided with the short-circuited coil 46 or the reverse polarity coil 48 on the end surface side, the analysis results as shown in FIG. 24 were obtained.

10 rotary electric machine stator core (stator core), 13 stator yoke, 14 tooth, 16 slot, 30, 30a to 30h induction heating device, 31, 31a center core, 33 excitation coil, 35, 35a end core, 40, 40a first heat insulation Part 42 Second heat insulating part 44 Metal ring 46 Short-circuiting coil 48 End surface side reverse polarity coil 50 Outer circumference side reverse polarity coil 52 Third heat insulation part 54, 54a, 54b Outer circumference yoke 55 Cylindrical part 56 Plate Part 57 Yoke element 57a, 57b Plate part 58 First yoke element 59 Second yoke element 60, 60a, 60b, 60c Induction heating device 61 Hole 62 Disk part 63 Radial plate part.

Claims (6)

An induction heating device for a rotating electric machine stator core, comprising: 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 center core disposed on the inner peripheral side of the rotating electric machine stator core and wound with an exciting coil;
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 first heat insulating portion disposed between the end core and the rotating electric machine stator core;
a second heat insulating portion disposed between the outer peripheral surface of the exciting coil and the rotating electric machine stator core,
Induction heating device for rotating electric machine stator core. In the induction heating device for a rotating electric machine stator core according to claim 1,
On the outer peripheral side of the two end cores, in the space on both axial end faces of the yoke, a metal ring continuous in the circumferential direction, a short-circuited coil whose winding start and winding end are short-circuited, or the excitation coil An end face side reverse polarity coil connected so as to have a reverse polarity is arranged,
Induction heating device for rotating electric machine stator core. In the induction heating device for a rotating electric machine stator core according to claim 1,
An outer-peripheral-side reverse-polarity coil connected to the excitation coil in a reverse polarity with a number of turns equal to or less than half the number of turns of the excitation coil is arranged on the outer periphery of the yoke.
Induction heating device for rotating electric machine stator core. In the induction heating device for a rotating electric machine stator core according to any one of claims 1 to 3,
Two plate portions are connected to both ends of the cylindrical portion so as to close the openings at both ends of the cylindrical portion, or an outer peripheral yoke configured to include a yoke element having a rectangular cross section includes the central core and the two ends. positioned opposite the axially outer surfaces of the two end cores over the end cores;
Induction heating device for rotating electric machine stator core. In the induction heating device for a rotating electric machine stator core according to any one of claims 1 to 4,
An axially penetrating hole is formed in the center of the central core and the end core, and a cooling liquid flows through the hole, or a cooling device having higher thermal conductivity than the central core and the end core. The central core is cooled by inserting a member,
Induction heating device for rotating electric machine stator core. A method for induction heating the teeth of the rotating electrical machine stator core using the induction heating device for the rotating electrical machine stator core according to any one of claims 1 to 5, comprising:
By supplying an alternating current to the excitation coil, magnetic flux is caused to flow through the central core and the two end cores and the teeth disposed between the two end cores, thereby generating magnetic flux for induction heating of the teeth. including steps,
An induction heating method for a rotating electric machine stator core.

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