Stator core of rotary electric machine, and rotary electric machine

Abstract

A stator core of a rotary electric machine according to this embodiment comprises an annular core back section (14) and a plurality of tooth sections (13) that extend to the inner diameter side of the core back section (14), with a magnetic shielding cover (50) being further provided to the outer circumference side of the core back section (14). This stator core of a rotary electric machine is provided with first and second end section expansion core sections (15), a refrigerant inlet (61) and a refrigerant outlet (62), first and second header flow passages (63), a tooth section flow passage (60), a plurality of tooth section inlets (64), and a plurality of tooth section outlets (65), and is configured such that a refrigerant which is supplied from outside flows in from the refrigerant inlet (61), flows in order through the first header flow passage (63), the plurality of tooth section inlets (64), the tooth section flow passage (60), the plurality of tooth section outlets (65), and the second header flow passage (63), and flows out to the outside from the refrigerant outlet (62).

Description

Stator Core of Rotating Electric Machine and Rotating Electric Machine

[0001] An embodiment of the present invention relates to a stator core of a rotating electric machine and a rotating electric machine.

[0002] An example of the structure of a conventional rotating electric machine will be described using FIGS. 12 and 13.

[0003] FIG. 12 is a diagram showing an example of a cross-sectional shape when a conventional rotating electric machine is viewed in the axial direction. FIG. 13 is a diagram showing an example of a cross-sectional shape when the conventional rotating electric machine shown in FIG. 12 is viewed in the circumferential direction.

[0004] The rotating electric machine corresponds to, for example, an electric motor or a generator, includes a stator 10 and a rotor 20, and is arranged concentrically. The rotor 20 rotates about a rotation axis 30. The rotor 20 is arranged at a certain distance from the stator 10, and a certain gap is provided between the stator 10 and the rotor 20.

[0005] The stator 10 is provided with slots 11 at regular intervals in the circumferential direction, and armature coils 12 are provided in the individual slots 11. An insulator (not shown) is provided between the slot 11 and the armature coil 12, and a wedge (not shown) for preventing the armature coil 12 from protruding is also provided.

[0006] In addition, FIG. 12 shows an example of a form in which the individual coil pieces constituting the armature coil 12 are laminated in the radial direction of the rotating electric machine within the slot 11, but there is also a form in which they are dispersed and arranged within the slot 11.

[0007] The stator core 10A in the stator 10 is composed of an annular core back portion and tooth portions arranged on the inner diameter side of the core back portion. A magnetic shielding cover (magnetic shield) 50 is provided on the outer peripheral side of the core back portion. The above-described slots 11 are formed between adjacent tooth portions. The individual coil pieces of the armature coil 12 are housed in the slot 11 in a state insulated by an insulator.

[0008] Conventionally, the stator core 10A of a rotating electric machine, for example, the stator core of an electric motor or generator, mainly uses metal as its material. The stator core is made of a soft magnetic material such as electromagnetic steel sheet, and forms a bulk body made of these materials or a laminated structure made by stacking them.

[0009] The main role and effect of the stator core is to act as a path for the magnetic field generated inside the rotating electric machine, thereby providing driving force. Since iron conducts magnetic fields approximately 1000 times more easily than air, using a core allows for efficient transfer of magnetic flux between the rotor and the armature coils of the stator, reducing leakage flux and increasing driving force.

[0010] The stator core not only provides electrical effects but also plays an important role in structural design. Specifically, the stator core has multiple slots 11 arranged circumferentially, mainly on the inner diameter side of its structure. The armature coils 12 are housed in these slots, thereby providing resistance to external stresses such as vibrations that the stator, which is assembled from all its components into a complete structure, is subjected to, and thus improving its mechanical strength.

[0011] Furthermore, the stator core serves as a reference for the relative positional relationships between various parts, such as gaps, as well as for positioning such as concentricity and shaft alignment. This helps to reduce manufacturing dimensional tolerances when assembling electric motors or generators, thereby promoting improved accuracy.

[0012] Depending on the type of rotating electric machine, the stator may experience a large magnetic field from the rotor. In such cases, eddy current losses in the stator's metal core become excessive, causing the temperature to rise. Specifically, when using an electrical conductor such as metal or laminated electrical steel sheets in the stator core of an electric motor or generator equipped with a certain type of rotor, the loss causes the temperature to rise, thermally affecting the armature coil of the stator, which has temperature limitations, posing a significant problem.

[0013] On the other hand, one could consider adopting a coreless design for this type of electric motor, eliminating the core around the armature coil to avoid heat generation due to eddy currents in that area. However, adopting a coreless design would make assembly difficult, such as determining dimensions and positioning during manufacturing, and would require assembly jigs, raising concerns about increased processing time.

[0014] One possible solution to the above problem is to use a core made of a material that does not generate or can reduce eddy current losses. Since electrical conductivity is strongly correlated with eddy current losses, eddy current losses can be suppressed by using a material with low or zero electrical conductivity, such as a non-metallic material (such as a resin). While this makes it possible to suppress eddy current losses, the aforementioned non-metallic materials (such as resins) generally have lower thermal conductivity than metallic materials. Therefore, without some ingenuity, the heat transmitted and released through the core using the armature coil as a heat source may cause an excessive temperature rise inside or around the armature coil.

[0015] Furthermore, when such materials are used to construct the core, a magnetic shielding cover 50 is required to cover the outer circumference of the stator core 10A, as shown in Figure 13, in order to prevent magnetism from leaking to the outside. Eddy currents are generated in this magnetic shielding cover 50, causing it to generate heat, which can lead to an excessive temperature rise in the magnetic shielding cover and its surroundings.

[0016] To solve this problem, methods for cooling the inner or outer diameter side of the stator can be considered, such as forced air cooling with auxiliary equipment like a fan, or self-cooling, where airflow generated by the rotation of the motor is facilitated by an outer shell structure with irregularities. However, both methods involve the installation of auxiliary equipment and the burden on structural design. Furthermore, depending on the location and environment in which the motor is installed, miniaturization and weight reduction may be required, and the number of parts must be kept to a minimum while ensuring the required characteristics of the motor.

[0017] This invention has been made in view of the above circumstances, and aims to provide a stator core for a rotating electric machine and a rotating electric machine that can improve cooling performance with a simple configuration.

[0018] The stator core of a rotating electric machine according to this embodiment comprises an annular core back portion and a plurality of teeth portions extending toward the inner diameter side of the core back portion, and further a magnetic shielding cover is provided on the outer circumference side of the core back portion, the stator core of a rotating electric machine comprising: first and second end-extended core portions having a structure in which each of the axial ends of the stator core is extended toward the outer diameter side; refrigerant inlet and refrigerant outlet provided in the first and second end-extended core portions, respectively; first and second header passages provided in each of the first and second end-extended core portions and formed so that the refrigerant flows in the circumferential direction; and the plurality of teeth The device comprises toothed section flow paths formed so that the refrigerant flows axially within each section, a plurality of toothed section inlets connecting the first header flow path and the toothed section flow paths, and a plurality of toothed section outlets connecting the toothed section flow paths and the second header flow path. The device is configured such that the refrigerant supplied from the outside flows in through the refrigerant inlets, sequentially through the refrigerant inlets, the first header flow path, the plurality of toothed section inlets, the toothed section flow paths, the plurality of toothed section outlets, the second header flow path, and the refrigerant outlet, and flows out to the outside through the refrigerant outlets.

[0019] Figure 1 is a perspective view showing a part of the stator of a rotating electric machine according to an embodiment. Figure 2 is an axial cross-sectional view showing an example of the cross-sectional shape of a part of the stator of the rotating electric machine shown in Figure 1 when viewed in the circumferential direction. Figure 3 is a diagram showing the cross-sectional shape of the part of the stator core 10A that includes the first end extension core portion 15. Figure 4 is a diagram showing the cross-sectional shape of the central part of the stator core 10A. Figure 5 is an axial cross-sectional view showing another example of the cross-sectional shape of a part of the stator of the rotating electric machine shown in Figure 1 when viewed in the circumferential direction. Figure 6 is a diagram showing a modified shape of the refrigerant reservoir 66 shown in Figure 5. Figure 7 is a diagram showing a first modified shape of the refrigerant inlet 61. Figure 8 is a diagram showing a second modified shape of the refrigerant inlet 61. Figure 9 is a diagram showing a modified shape of the first header flow path 63. Figure 10 is a graph showing the "flow velocity distribution" of the refrigerant superimposed on an axial cross-sectional view of a part of the stator 10. Figure 11 is a graph showing the "temperature distribution" of the refrigerant superimposed on an axial cross-sectional view of a part of the stator 10. Figure 12 shows an example of the cross-sectional shape of a conventional rotating electric machine when viewed in the axial direction. Figure 13 shows an example of the cross-sectional shape of the conventional rotating electric machine shown in Figure 12 when viewed in the circumferential direction. Embodiment

[0020] The embodiments will be described below with reference to the drawings. Figure 12, mentioned earlier, will also be referenced here.

[0021] (Configuration) The basic structure of the rotating electric machine according to this embodiment is the same as that described in Figure 12. However, the structure of the stator core is different from that of the conventional one. The following will focus on the parts that differ from the conventional structure described above.

[0022] Figure 1 is a perspective view showing a part of the stator of a rotating electric machine according to an embodiment. Figure 2 is an axial cross-sectional view showing an example of the cross-sectional shape of a part of the stator of the rotating electric machine shown in Figure 1 when viewed in the circumferential direction.

[0023] The structure shown in Figure 1 is part of the stator 10. In reality, a single stator 10 is formed by connecting multiple structures identical to those in Figure 1 in the circumferential direction. The example of the structure shown in Figure 1 illustrates a case where there are six teeth 13.

[0024] The stator core 10A of the rotating electric machine according to this embodiment has a basic structure comprising an annular core back portion 14 and a plurality of teeth portions 13 extending radially from the core back portion 14, and further comprises a magnetic shielding cover (magnetic shield) 50 on the outer circumference of the core back portion 14 that blocks magnetism from moving from the inside to the outside.

[0025] Furthermore, the stator core 10A includes first and second end-extended core portions 15, each having a structure in which the axial ends of the stator core 10A are extended outwards. The first and second end-extended core portions 15 are arranged to sandwich the magnetic shielding cover 50 from both its axial ends.

[0026] Furthermore, the first and second end extension core portions 15 are provided with first and second header flow paths 63, respectively. The first and second header flow paths 63 are formed so that the refrigerant flows in the circumferential direction. In Figure 1, for convenience, a cross-section of the first header flow path 63 is shown.

[0027] Furthermore, the outer diameter side of each of the first and second end-expanded core portions 15 is provided with a refrigerant inlet 61 through which refrigerant supplied from the outside flows in, and a refrigerant outlet 62 through which refrigerant flows out to the outside.

[0028] Figure 2 shows the aforementioned magnetic shielding cover 50, as well as the tooth section flow path 60, tooth section inlet 64, tooth section outlet 65, etc., which are located inside the stator core 10A. These will be explained later.

[0029] Figure 3 shows the cross-sectional shape of the portion of the stator core 10A that includes the first end extension core portion 15. The cross-sectional shape of the portion of the stator core 10A that includes the second end extension core portion 15 is the same as in Figure 3, so it is not shown here. Figure 4 shows the cross-sectional shape of the central portion of the stator core 10A.

[0030] Figures 3 and 4 show the refrigerant inlet 61 and the first header flow path 63 mentioned above. In addition, the teeth section flow path 60, teeth section inlet 64, and refrigerant reservoir 66, which will be described later, are also shown. Figure 4 shows the teeth section flow path 60 and the refrigerant reservoir 66.

[0031] An armature coil 12 is provided in each slot of the stator 10. An insulator 17 is provided between the slot 11 and the armature coil 12, and a wedge 16 is also provided to prevent the armature coil 12 from popping out.

[0032] As can be seen from Figures 2 to 4, each of the multiple tooth sections 13 is provided with a tooth section flow path 60 that is open to allow the refrigerant to flow in the axial direction. Furthermore, multiple tooth section inlets 64 are provided to connect the first header flow path 63 and the tooth section flow path 60, and multiple tooth section outlets 65 are provided to connect the tooth section flow path 60 and the second header flow path 63.

[0033] In this configuration, the refrigerant supplied from the outside flows in through the refrigerant inlet 61, then sequentially through the first header flow path 63 provided in the first end expansion core section 15, the multiple tooth section inlets 64, the tooth section flow path 60, the multiple tooth section outlets 65, and the second header flow path 63 provided in the second end expansion core section 15, before flowing out to the outside through the refrigerant outlet 62. The refrigerant may be a liquid (e.g., oil) or a gas.

[0034] Specifically, the refrigerant flowing in from the refrigerant inlet 61 enters the first header flow path 63, flows circumferentially through it, enters the multiple tooth inlets 64 provided in each of the multiple tooth sections 13, and flows toward the inner diameter. Furthermore, the refrigerant flows axially through the tooth flow paths 60 provided in each of the multiple tooth sections 13. The refrigerant flowing in this manner cools the stator core 10A body, the armature coil 12, and the magnetic shielding cover 50. The refrigerant that has passed through the multiple tooth flow paths 60 flows toward the outer diameter, enters the second header flow path 63 from the multiple tooth outlets 65, merges, and is discharged from the refrigerant outlet 62.

[0035] In this embodiment, by expanding both ends of the stator core 10A toward the outer diameter, the flow area from the refrigerant inlet 61, where the refrigerant flow rate is highest, to the first header flow path 63 can be enlarged, making it possible to increase the refrigerant flow rate and perform efficient cooling. Furthermore, in this embodiment, since the magnetic shielding cover (magnetic shield) 50 is sandwiched between the first and second end-expanded core portions 15, it is possible to enhance the cooling of the magnetic shield as well.

[0036] In this embodiment, an example is shown in which six tooth sections 13 (six tooth section flow paths 60, six tooth section inlets 64, and six tooth section outlets 65) are in communication. However, the embodiment is not limited to this example, and a configuration employing a different number of tooth sections 13 is also possible.

[0037] (Other features) As can be seen from Figure 3, the multiple toothed inlets 64 (and multiple toothed outlets 65) are formed such that the shape of part or all of the flow path widens towards the outer diameter. Therefore, pressure loss in that part can be reduced. This structure may be applied to both the multiple toothed inlets 64 and the multiple toothed outlets 65, or to either one of them.

[0038] Furthermore, as can be seen from Figures 2 to 4, two refrigerant reservoirs 66 are provided in a part of the tooth section inlet 64, the tooth section outlet 65, and the tooth section flow path 60. Figure 5 is an axial cross-sectional view showing another example of a cross-sectional shape when a part of the stator of the rotating electric machine shown in Figure 1 is viewed in the circumferential direction, and the cross-sectional shape of the part including the two refrigerant reservoirs 66 is shown. Figure 6 is a diagram showing a modified example of the shape of the refrigerant reservoir 66 shown in Figure 5.

[0039] The refrigerant reservoir 66 has a wider circumferential flow path than the flow paths of other parts. By widening the flow path, the refrigerant can flow more easily along the refrigerant reservoir 66, thereby making it possible to equalize the axial refrigerant flow rate and refrigerant temperature. This structure may be applied to all of the tooth section inlet 64, tooth section outlet 65, and tooth section flow path 60, or to any one of them.

[0040] Further, by arranging part or all of such a refrigerant reservoir portion 66 so as to extend obliquely with respect to the axial direction as shown in FIGS. 5 and 6, it becomes possible to efficiently supply refrigerant to a portion where the temperature of the armature coil, such as the inner diameter side, becomes high and to efficiently cool it.

[0041] (Various modifications) FIG. 7 is a diagram showing a first modification of the refrigerant inlet 61. Since the modification of the refrigerant outlet 62 is the same as that shown in FIG. 7, the illustration thereof is omitted here.

[0042] In this modification, as can be seen from FIG. 7, the refrigerant inlet 61 (and the refrigerant outlet 62) is formed such that the shape of part or all of the flow path 61a has a flow path width that widens toward the inner diameter side. Therefore, the pressure loss of that portion can be reduced. Such a structure may be applied to both the refrigerant inlet 61 and the refrigerant outlet 62, or may be applied to either one of them.

[0043] FIG. 8 is a diagram showing a second modification of the refrigerant inlet 61. Since the modification of the refrigerant outlet 62 is the same as that shown in FIG. 8, the illustration thereof is omitted here.

[0044] Since the refrigerant that cools the stator core 10A converges and passes through the refrigerant inlet 61 (and the refrigerant outlet 62), the flow velocity is high, and a large flow velocity distribution may occur in the flow path. As a method for solving this, a mechanism (flow velocity distribution normalization mechanism) 61b for normalizing the flow velocity distribution, such as a wire mesh, is provided at the refrigerant inlet 61 or the refrigerant outlet 62 or both of them. Thereby, the pressure loss of that portion can be reduced. Such a structure may be applied to both the refrigerant inlet 61 and the refrigerant outlet 62, or may be applied to either one of them.

[0045] FIG. 9 is a diagram showing a modification of the first header flow path 63. Since the modification of the second header flow path 63 is the same as that shown in FIG. 9, the illustration thereof is omitted here.

[0046] In the cross-sectional view shown in FIG. 3, the first header flow path 63 (and the second header flow path 63) provided in the end expansion core portion 15 has a structure with a constant radial flow path width, but part or all of the shape of the header flow path 63 is formed such that the flow path width widens as it approaches the refrigerant inlet 61 or the refrigerant outlet 62. Therefore, the pressure loss in that portion can be reduced. Such a structure may be applied to both the first header flow path 63 and the second header flow path 63, or may be applied to either one of them.

[0047] (Verification Results) Referring to FIGS. 10 and 11, the results of verifying the effects of the present embodiment will be described.

[0048] Here, the “flow velocity distribution” and “temperature distribution” of the refrigerant were verified using the axial cross-sectional view of the stator 10 of the rotating electric machine described above. Here, a shape in which the two refrigerant reservoir portions 66 extend horizontally rather than obliquely was adopted.

[0049] FIG. 10 is a graph in which the “flow velocity distribution” of the refrigerant is superimposed on a partial axial cross-sectional view of the stator 10 described above. FIG. 11 is a graph in which the “temperature distribution” of the refrigerant is superimposed on a partial axial cross-sectional view of the stator 10 described above. In each figure, the teeth portion inlet 64 described above exists in the upper left part of the figure, the teeth portion flow path 60 described above exists in the central part, and the teeth portion outlet 65 described above exists in the upper right part. Also, the two refrigerant reservoir portions 66 described above exist so as to extend in the axial direction.

[0050] In FIG. 10, the flow velocity of the refrigerant is represented by the shade (gray scale) of black color. Here, the higher the flow velocity of the refrigerant, the whiter it is represented, and the lower the flow velocity of the refrigerant, the blacker it is represented. Also, the arrows in the figure indicate the direction of the refrigerant flow.

[0051] From the graph of FIG. 10, it can be seen that, in particular, the places where the refrigerant flows along the two refrigerant reservoir portions 66 have a large flow velocity. The periphery of the teeth portion inlet 64 and the periphery of the teeth portion outlet 65 also have a large flow velocity.

[0052] In Figure 11, the temperature of the refrigerant is represented by shades of black and white (grayscale). Here, areas with higher temperatures are represented by white, and areas with lower temperatures are represented by black.

[0053] From the graph in Figure 11, it can be seen that the temperature is particularly low where the refrigerant flows along the two refrigerant reservoirs 66 (i.e., where the refrigerant flow velocity is high). It can also be seen that low-temperature refrigerant is supplied to the downstream side along the refrigerant reservoirs 66. The refrigerant temperature increases downstream as the stator core 10A is cooled, but it can be confirmed that the low-temperature refrigerant that flows along the refrigerant reservoirs 66 spreads downstream, supplying low-temperature refrigerant to the downstream side.

[0054] It is presumed that this excellent cooling effect is greatly influenced by the presence of the tooth section inlet 64, tooth section flow path 60, and tooth section outlet 65, as well as the presence of the first and second header flow paths 63 and the refrigerant reservoir 66, which are in communication with the tooth section inlet 64 and tooth section outlet 65, respectively.

[0055] (Summary) As described in detail above, according to the embodiment, it is possible to provide a stator core for a rotating electric machine and a rotating electric machine that can improve the cooling performance of the stator core, armature coil, and magnetic shielding cover with a simple configuration.

[0056] For example, according to this embodiment, by expanding both ends of the stator core 10A toward the outer diameter, the flow area from the refrigerant inlet 61, where the refrigerant flow rate is highest, to the first header flow path 63 can be enlarged, making it possible to increase the refrigerant flow rate and perform efficient cooling. Furthermore, according to this embodiment, since the magnetic shielding cover (magnetic shield) 50 is sandwiched between the first and second end-expanded core portions 15, it is possible to enhance the cooling of the magnetic shield as well.

[0057] Furthermore, according to the embodiment, while maintaining the manufacturing dimensional accuracy of the stator core or rotating electric machine, eddy current losses generated in the stator core can be reduced, and in addition to cooling the armature coil, the rotor installed on the inner diameter side of the stator core or the structure installed on the outer diameter side can be efficiently cooled.

[0058] Furthermore, according to the embodiment, it is possible to reduce the number of parts as much as possible while ensuring the characteristics required for a rotating electric machine, thereby achieving miniaturization and weight reduction.

[0059] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

Claims

1. A stator core for a rotating electric machine comprising an annular core back portion (14) and a plurality of tooth portions (13) extending toward the inner diameter side of the core back portion (14), and further provided with a magnetic shielding cover (50) on the outer circumference side of the core back portion (14), wherein the stator core comprises: first and second end-extended core portions (15) having a structure in which each of the axial ends of the stator core is extended toward the outer diameter side; refrigerant inlet (61) and refrigerant outlet (62) provided in the first and second end-extended core portions (15), respectively; first and second header flow paths (63) provided in each of the first and second end-extended core portions (15) and formed so that the refrigerant flows in the circumferential direction; tooth portion flow paths (60) formed so that the refrigerant flows in the axial direction inside each of the plurality of tooth portions (13); and a plurality of tooth portion inlets (64) connecting the first header flow path (63) and the tooth portion flow paths (60), A stator core for a rotating electric machine, comprising: a plurality of toothed outlets (65) that connect the toothed passage (60) and the second header passage (63), wherein a refrigerant supplied from the outside flows in from the refrigerant inlet (61), sequentially through the first header passage (63), the plurality of toothed inlets (64), the toothed passage (60), the plurality of toothed outlets (65), and the second header passage (63), and flows out to the outside from the refrigerant outlet (62).

2. A stator core for a rotating electric machine according to claim 1, wherein at least one of the plurality of toothed inlets (64) and the plurality of toothed outlets (65) is formed such that the shape of a part or all of it is such that the flow path width widens towards the outer diameter side.

3. A stator core for a rotating electric machine according to claim 1, wherein at least one of the refrigerant inlet (61) and the refrigerant outlet (62) is formed such that a part or all of its shape is such that the flow path width widens towards the inner diameter side.

4. A stator core for a rotating electric machine according to claim 1, wherein at least one of the refrigerant inlet (61) and the refrigerant outlet (62) is provided with a mechanism (61b) for leveling the flow velocity distribution.

5. A stator core for a rotating electric machine according to claim 1, wherein at least one of the first and second header flow paths (63) is formed such that the width of the flow path widens as it approaches the refrigerant inlet (61) or the refrigerant outlet (62).

6. A stator core for a rotating electric machine according to claim 1, wherein at least one of the first and second header flow channels (63) and the teeth flow channel (60) is provided with a refrigerant reservoir (66) in a part thereof, the circumferential flow channel width being expanded.

7. A stator core for a rotating electric machine according to claim 6, wherein at least a portion of the refrigerant reservoir (66) is configured to extend obliquely with respect to the axial direction.

8. A stator core for a rotating electric machine according to claim 1, wherein the first and second end extension core portions (15) are arranged to sandwich the magnetic shielding cover (50) from both axial ends.

9. A rotating electric machine comprising a stator having an armature coil (12) provided on a stator core (10A) according to any one of claims 1 to 8, and a rotor (20) disposed at a certain distance from the stator.

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