Stator core support structure and rotating electrical machine

Abstract

A stator core support structure (20) according to an embodiment of the present invention is applied to a stator of a rotating electrical machine comprising a stator core (21) and a magnetic shield (22) disposed on the outer-diameter side of the stator core (21), the stator core support structure being provided with: two core retainers (25), which are attached so as to clamp both the stator core (21) and the magnetic shield (22) from both sides in the axial direction of the stator, and which have extension parts (25a) extending farther on the outer-diameter side of the stator than the outer peripheral surface of the magnetic shield (22); and a support member (26) which is integrally attached to a part of the surface on the outer peripheral side of the magnetic shield (22) and a part of the surface of each of the extension parts (25a) of the two core retainers (25).

Description

Stator Core Support Structure and Rotating Electric Machine

[0001] Embodiments of the present invention relate to a stator core support structure and a rotating electric machine.

[0002] Conventionally, a stator core that houses armature coils of a stator of a rotating electric machine, for example, a stator core of a motor or a generator, mainly uses metal as its material. Since the stator core serves as a path for magnetic fields, it is made of a soft magnetic material such as electromagnetic steel sheets, and forms a bulk body composed of them or a laminated structure in which they are laminated.

[0003] The main role and effect of the stator core is to serve as a path for magnetic fields generated inside the rotating electric machine and provide a driving force. Since iron is approximately 1000 times more permeable to magnetic fields than air, using a core enables efficient transfer of magnetic flux between the rotor and the armature coils of the stator, reduces leakage magnetic flux, and increases the driving force.

[0004] In addition to its electromagnetic role, the stator core also plays an important role in structural design. That is, the stator core has a plurality of grooves (hereinafter referred to as "slots") arranged in the circumferential direction mainly on the inner diameter side of the structure, and by housing the armature coils in these slots, it realizes the resistance force against external stresses such as vibrations received by the stator, which is a complete assembly of all components, and plays a role in improving mechanical strength.

[0005] Further, the stator core serves as a reference for the relative positional relationship such as the gap between each part, concentricity, and shaft extension, etc., reduces the manufacturing dimension tolerance when assembling a motor or a generator, and helps improve accuracy. Also, improving manufacturing accuracy increases the possibility of realizing a product with motor performance close to the design.

[0006] The stator core of a rotating electric machine, such as the stator core of an electric motor, often has various structures attached to its outer circumference. Among the structures attached to the stator core are support structures that provide stable support for the stator core. When attaching support structures to the stator core, joining or welding is generally used. In addition, the stator core is usually fixed by laminating and pressing electromagnetic steel sheets in the axial direction, then welding in the lamination direction on the outer circumference, and this external rotation process. Furthermore, in addition to external rotation, a plate material with a nose or legs, which is necessary during outfitting, may be joined to the outer circumference of the stator core by welding. In that case, depending on the type of electric motor applied, heat may be generated in the metal mass formed at the weld due to the influence of magnetic flux from the rotor.

[0007] Specifically, when a metal mass is formed in the welded area due to the heat of welding, and then exposed to a strong magnetic field originating from the rotor, eddy current losses occur in the metal mass formation area, causing heat generation. These losses reduce the efficiency of the rotating electric machine, and surrounding structures are also affected by the heat, further degrading the performance of the rotating electric machine.

[0008] For the reasons stated above, this heat generation is one of the major challenges in improving the efficiency of rotating electric machines, and careful attention must be paid to the method of fixing the stator core and the location of the stator.

[0009] This invention has been made in view of the above circumstances, and aims to provide a stator core support structure and a rotating electric machine that can reduce heat generation.

[0010] The stator core support structure of the embodiment is a stator core support structure applied to the stator of a rotating electric machine comprising a stator core and a magnetic shield disposed on the outer diameter side of the stator core, and comprises two core retainers that are attached so as to sandwich both the stator core and the magnetic shield from both sides in the stator axial direction and have extensions that extend toward the outer diameter side of the stator beyond the outer peripheral surface of the magnetic shield, and a support member that is integrally attached to a part of the outer peripheral surface of the magnetic shield and a part of the surface of each of the extensions of the two core retainers.

[0011] Figure 1 is a schematic diagram showing an example of the configuration of a stator core support structure applied to the stator of a rotating electric machine according to an embodiment. Figure 2 is a diagram showing an example of the external appearance of a rotating electric machine including a stator to which the stator core is fixed by the stator core support structure shown in Figure 1. Figure 3 is a diagram showing an enlarged view of the structure near the central part 10 of the rotating electric machine shown in Figure 2. Figure 4 is a diagram showing a further enlargement of the structure near the central part 10 of the rotating electric machine shown in Figure 3, and also showing a part of the cross-sectional shape. Figure 5 is a schematic diagram showing the axial cross-sectional shape near the axial center of the stator according to the first modified example. Figure 6 is a diagram showing the axial cross-sectional shape near the axial center of the stator according to the second modified example. Embodiment

[0012] The embodiments will be described below with reference to the drawings.

[0013] (Basic Configuration) Figure 1 is a schematic diagram showing an example of the configuration of a stator core support structure applied to the stator of a rotating electric machine according to the embodiment. Figure 2 is a diagram showing an example of the external appearance of a rotating electric machine including a stator to which the stator core is fixed by the stator core support structure shown in Figure 1.

[0014] The stator core support structure 20 shown in Figure 1 is applied to a stator comprising a stator core 21 and a magnetic shield 22 positioned on the outer diameter side of the stator core 21. The stator has two side fixing members 23 attached to both sides of the stator core 21 and the magnetic shield 22 in the stator axial direction. Iron or aluminum is used as the material for the stator core 21 and the side fixing members 23. Silicon steel sheet or a magnetic material containing iron, cobalt, etc. is used for the magnetic shield 22.

[0015] The stator core support structure 20 shown in Figure 1 is a structure used to stably support and fix the stator core 21, and is provided in multiple units (for example, four or six units) at regular intervals in the circumferential direction of the stator, in a point-symmetric relationship with respect to the axis.

[0016] The stator core support structure 20 includes various components such as two core retainers 25, a support member 26, and a fastening member 27, and has multiple welded joints 31, 32, etc., where welding is performed at locations requiring connection between components. These welded joints are located at least on the outer diameter side of the stator beyond the magnetic shield 22, in order to minimize the effects of heat generation on the stator core 21 side due to eddy current losses associated with the field current generated from the rotor. Specifically, the position, range, number, and capacity of each welded joint are determined after taking into account the amount of heat input to the metal mass formed in the welded joint. The stator core 21 is designed to have no welded joints. Details of the welded joints will be described later.

[0017] The fastening member 27 is also positioned at a certain distance from the magnetic shield 22 in order to minimize the effects of heat generation due to eddy current losses on the stator core 21 side.

[0018] The two core retainers 25 are mounted so as to sandwich both the stator core 21 and the magnetic shield 22 from both sides in the stator axial direction, and have extensions 25a that extend toward the outer diameter of the stator beyond the outer circumferential surface of the magnetic shield 22. The outer edge of the extension 25a on the outer diameter side of the stator is coupled and fixed to a bracket 24, which will be described later.

[0019] The support member 26 is a plate material with a "U" shape and is integrally attached to a part of the outer surface of the magnetic shield 22 and a part of the surface of each of the extensions 25a of the two core retainers 25. The fastening member 27 is equivalent to, for example, a fastening bolt and firmly connects and fixes the extensions 25a of the two core retainers 25 to the support member 26.

[0020] The support members 26 and fastening members 27 are made of SUS (Steel Use Stainless), which guarantees a certain level of strength, while the core retainer 25 is made of aluminum, which contributes to weight reduction.

[0021] The rotating electric machine shown in Figure 2 corresponds to, for example, an electric motor or a regenerative motor, and comprises a stator and a rotor positioned on its inner diameter side. Although not shown here, the rotor rotates around a rotation axis, and the rotor is positioned at a certain distance from the stator, with a certain gap between the stator and the rotor.

[0022] Furthermore, in the central part 10 of the rotating electric machine shown in Figure 2, it can be seen that the magnetic shield 22, two side fixing members 23, a support member 26, and a fastening member 27, as well as various welded parts 31 to 33, are present. In addition, at the ends 11 and 12 located on both sides of the central part 10 in the direction of the stator axis, it can be seen that there are two core retainers 25, as well as brackets 24 that cover the various mechanisms inside the ends 11 and 12. The outer edges of the core retainers 25 on the stator outer diameter side are connected and fixed to the brackets 24. In Figure 2, the ends of the armature coils 28, which will be described later, are partially visible through a window provided in the brackets 24. Note that in Figure 2, the brackets 24 are represented as semi-transparent so that the internal structure of the brackets 24 can be seen through them.

[0023] (Details of the stator core support structure and its surrounding structure) Next, with reference to Figures 3 and 4, the structure of the stator core support structure 20 and its surrounding structure will be described in more detail.

[0024] Figure 3 is an enlarged view of the structure near the central part 10 of the rotating electric machine shown in Figure 2. Figure 4 is a further enlarged view of the structure near the central part 10 of the rotating electric machine shown in Figure 3, and also shows some of the cross-sectional shapes. In these figures, elements common to Figures 1 and 2 are denoted by the same reference numerals.

[0025] As shown in Figure 4, the stator is provided with slots 29 at regular intervals in the circumferential direction, and an armature coil 28 is provided in each slot 29. An insulator (not shown) is provided between the slots 29 and the armature coil 28, and a wedge (not shown) is also provided to prevent the armature coil 28 from popping out. In addition, a refrigerant flow path (not shown) is provided inside the stator core 21 of the stator, with an opening for the flow of a refrigerant (cooling medium).

[0026] Figures 3 and 4 illustrate three types of welded joints 31 to 33.

[0027] The welded joint 31 connects the support member 26 and the magnetic shield 22, fixing the support member 26 to the magnetic shield 22.

[0028] The welded joint 32 connects the side fixing member 23 and the core holder 25, fixing the side fixing member 23 to the core holder 25.

[0029] The welded portion 33 is formed by welding at the boundary between the portion of the support member 26 that is attached to a part of the outer surface of the magnetic shield 22 and the side fixing member 23, and the portion that is attached to a part of the surface of the extended portion of the core retainer 25. The welded portion 33 prevents the support member 26 from being separated at the boundary.

[0030] Furthermore, the portion of the support member 26 that is attached to a part of the surface of the extended portion of the core retainer 25 is fastened to the support member 26 by a fastening member 27.

[0031] In welding to form welds 31-33, the base material and the welding material are melted together and alloyed to fix them in place. There are various methods for this, but all of them involve a decrease in the properties of the base material depending on the area affected by welding (depth direction). Therefore, care should be taken to consider the affected area in order to minimize the decrease in the properties of the rotating electric machine. The position, range, number, and capacity of each weld in welds 31-33 are determined, as described above, taking into account the amount of heat input to the metal block.

[0032] The support member 26 and the two core retainers 25 (as well as the fastening member 27 and welded parts 31-33) configured in this way play a role in stably fixing the structure consisting of the magnetic shield 22, the side fixing member 23, and the stator core 21.

[0033] Next, we will introduce two variations regarding the arrangement of the support member 26.

[0034] (First Modified Example) Figure 5 is a schematic diagram showing the axial cross-sectional shape near the axial center of the stator according to the first modified example.

[0035] As shown in Figure 5, a magnetic shield 22 is positioned on the outer diameter side of the stator core 21 via a fitting portion 42, and a support member 26 is positioned on the outer diameter side of the magnetic shield 22. The magnetic shield 22 has a pre-formed build-up portion 41 of a predetermined thickness, and the support member 26 is fixed by being embedded in the build-up portion 41. The material of the build-up portion 41 is the same as that of the magnetic shield 22.

[0036] The support member 26 is joined to the magnetic shield 22 by welding. Before welding begins, the support member 26 is positioned on top of the build-up portion 41 and is on the outer diameter side of the position shown in Figure 5. As the build-up portion 41 melts during welding, the support member 26 is embedded in the build-up portion 41 as shown in Figure 5 and moves toward the inner diameter side. Once melting is complete, the support member 26 is stably fixed within the build-up portion 41.

[0037] With this configuration, the support member 26 is firmly fixed to the magnetic shield 22, thereby stably supporting the magnetic shield 22 and the stator core 21.

[0038] (Second Modification) Figure 6 is a schematic diagram showing the axial cross-sectional shape near the axial center of the stator according to the second modification.

[0039] As shown in Figure 6, a magnetic shield 22 is positioned on the outer diameter side of the stator core 21 via a fitting portion 42, and a support member 26 is positioned on the outer diameter side of the magnetic shield 22. In addition, tabs 51 are pre-formed on the magnetic shield 22 at a position that does not interfere with the installation of the support member 26. The material of the tabs 51 is the same as that of the magnetic shield 22. The tabs 51 also have through holes 52 for passing a support column. In this case, the support column may be made of resin. The tabs 51 may have a shape that extends in the direction of the stator axis, but for weight reduction, multiple tabs may be arranged at regular intervals in the direction of the stator axis. Both ends of the support column that passes through the through holes 52 are fixed to the two core retainers 25 described above.

[0040] By configuring it in this way, the support column passing through the through-hole 52 contributes to stably supporting the magnetic shield 22 and the stator core 21, so that the individual support members 26 can be made smaller and the weight can be reduced.

[0041] As described in detail above, according to the embodiment, it is possible to provide a stator core support structure and a rotating electric machine capable of reducing heat generation.

[0042] For example, by adopting the configuration described in the embodiment, it is possible to reduce the weight of the rotating electric machine, ensure the mechanical strength in the axial and radial directions of the stator, and reduce the influence of heat generation due to eddy current loss on the stator core side accompanying the field current generated from the rotor, thereby improving the performance of the rotating electric machine.

[0043] In addition, according to the embodiment, while maintaining the manufacturing dimensional accuracy of the stator core or the rotating electric machine, the eddy current loss generated in the stator core can be reduced, and in addition to cooling the armature coil, cooling of the rotor installed on the inner diameter side of the stator core or cooling of the structure installed on the outer diameter side can be efficiently performed.

[0044] Also, according to the embodiment, within the range of ensuring the characteristics required for the rotating electric machine, the number of parts can be suppressed as much as possible, and miniaturization and weight reduction can be achieved.

[0045] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Claims

1. A stator core support structure (20) applied to the stator of a rotating electric machine, comprising a stator core (21) and a magnetic shield (22) disposed on the outer diameter side of the stator core (21), the stator core support structure comprising: two core retainers (25) mounted so as to sandwich both the stator core (21) and the magnetic shield (22) from both sides in the stator axial direction, and having extensions (25a) that extend toward the outer diameter side of the stator beyond the outer peripheral surface of the magnetic shield (22); and a support member (26) integrally attached to a part of the outer peripheral surface of the magnetic shield (22) and a part of the surface of each of the extensions (25a) of the two core retainers (25).

2. The stator core support structure according to claim 1, wherein at least a portion of the support member (26) has a plurality of welded joints (31, 33), and the plurality of welded joints (31, 33) are located on the outer diameter side of the stator than the magnetic shield (22).

3. The stator core support structure according to claim 2, wherein the plurality of welded parts (31, 33) include a welded part (31) that joins the support member (26) and the magnetic shield (22).

4. The stator core support structure according to claim 2, wherein the plurality of welded parts (31, 33) include a welded part (33) that is welded at the boundary between a portion of the support member (26) that is attached to a portion of the outer surface of the magnetic shield (22) and a portion of the extensions (25a) of the two core retainers (25) that are attached to a portion of the surface.

5. The stator core support structure according to claim 1, further comprising two side fixing members (23) attached to both sides of the stator core (21) and the magnetic shield (22) in the stator axis direction, and a welded portion (32) that joins the two side fixing members (23) and the two core retainers (25), respectively.

6. The stator core support structure according to claim 1, further comprising a fastening member (27) that connects the respective extensions (25a) of the two core retainers (25) to the support member (26).

7. The stator core support structure according to claim 1, wherein the support members (26) are provided in multiple quantities at regular intervals in the circumferential direction of the stator.

8. The stator core support structure according to claim 1, wherein the magnetic shield (22) has a built-up portion (41) formed thereon with a predetermined thickness, and the support member (26) is fixed by being embedded in the built-up portion (41).

9. The stator core support structure according to claim 1, wherein the magnetic shield (22) has ear plates (51) formed in a position that does not interfere with the installation of the support member (26), the ear plates (51) have through holes (52) for passing a support column, and both ends of the support column that passes through the through holes (52) are fixed to the two core retainers (25).

10. A rotating electric machine comprising a stator whose stator core (21) is supported by a stator core support structure (20) according to any one of claims 1 to 9, and a rotor disposed at a certain distance from the stator.

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