Stator for rotating electrical machine

Abstract

To reduce the possibility of a coil wire coming off from a connecting pipe while making an insertion load relatively small when inserting and fitting the coil wire into the connecting pipe.SOLUTION: A stator for a rotating electrical machine includes a stator core, a coil wire having a rectangular cross section, and a connecting pipe having a hollow portion having a rectangular cross section, and the connecting pipe includes a first coil wire connected to a first connecting portion on one axial side of the connecting pipe and a second coil wire connected to a second connecting portion on the other axial side, at least one of the first connecting portion and the second connecting portion of the connecting pipe having an interference, the interference is an interference along a first direction of two directions along two orthogonal sides of the rectangle of the coil wire, and the interference along a second direction of the two directions is 0 or smaller than the interference along the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a stator for a rotating electric machine. [Background technology]

[0002] A technique is known in which a hollow connecting tube with a rectangular cross section is placed in a slot of a stator core, and one coil wire is fitted to one axial side of the hollow connecting tube, and another coil wire is fitted to the other axial side of the hollow connecting tube, thereby connecting these coil wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-126153 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-described conventional technology, it is difficult to reduce the possibility of the coil wire coming off the hollow connecting tube while keeping the insertion load relatively small when inserting and fitting the coil wire into the hollow connecting tube. If the insertion load is excessive, buckling deformation of the hollow connecting tube is likely to occur. Conversely, if the interference is reduced to reduce the insertion load, the possibility of the coil wire coming off the hollow connecting tube may increase.

[0005] Therefore, in one aspect, the present disclosure aims to reduce the possibility of the coil wire coming off the connection pipe while making the insertion load relatively small when inserting and fitting the coil wire into the connection pipe. [Means for solving the problem]

[0006] In one aspect, a stator core having a plurality of slots arranged in a circumferential direction; a coil wire having a rectangular cross section that passes through the plurality of slots and is wound around the stator core; a connecting pipe having a hollow portion with a rectangular cross section, the coil wire includes a first coil wire connected to one axial side of the connecting pipe and a second coil wire connected to the other axial side of the connecting pipe, the connecting pipe has a first connecting portion on one axial side to which the first coil wire is connected and a second connecting portion on the other axial side to which the second coil wire is connected, At least one of the first connection portion and the second connection portion has an interference, The interference is an interference along a first direction that increases the dimension of the connecting tube in the first direction, out of two directions along two orthogonal sides of the rectangle of the coil wire, and an interference along a second direction of the two directions is 0 or smaller than the interference along the first direction, in a stator for a rotating electric machine. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to reduce the possibility of the coil wire coming off the connection pipe while making the insertion load relatively small when inserting and fitting the coil wire into the connection pipe. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view of a rotating electric machine (stator) according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of a stator according to the present embodiment. [Figure 3] 3A and 3B are diagrams for explaining the configuration of coil pieces that form the stator coil. [Figure 4] 10 is an explanatory diagram showing an example of a method for connecting a connecting pipe to first coil pieces or second coil pieces. FIG. [Figure 5] 10 is a cross-sectional view schematically illustrating an example of a fitting portion between a connecting pipe and a first coil piece. FIG. [Figure 6] 10 is a cross-sectional view schematically showing another example of the fitting portion between the connecting pipe and the first coil piece. FIG. [Figure 7] FIG. 10 is a schematic cross-sectional view of a fitting portion according to a comparative example. [Figure 8] FIG. 10 is a diagram showing analysis results (part 1) relating to the effect of reducing the insertion load. [Figure 9] FIG. 10 is a diagram showing the analysis results (part 2) relating to the effect of reducing the insertion load. [Figure 10] FIG. 10 is an analysis result of a fitting structure in which the EW side interference is dominant, showing how the insertion load changes when the flatwise side interference is gradually increased from 0. [Figure 11] FIG. 10 is an analysis result of a fitting structure in which the interference on the FW side is dominant, showing how the insertion load changes when the interference on the edgewise side is gradually increased from 0. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not limiting. Furthermore, shapes and the like in the drawings may be partially exaggerated for the sake of explanation. Furthermore, in the drawings, for ease of viewing, reference symbols may be assigned only to some of the parts that exist with the same attribute.

[0010] FIG. 1 is a plan view of a rotating electrical machine (stator) according to this embodiment.

[0011] In this specification, the term "axial direction" refers to the direction along the rotation axis (symbol O) of the stator core 10 (rotor 150) (Z direction: see FIG. 1). One side of the axial direction is referred to as the Z1 direction side, and the other side as the Z2 direction side. The term "circumferential direction" refers to the circumferential direction (A direction) of the stator core 10. One side of the circumferential direction is referred to as the A1 direction, and the other side as the A2 direction. The term "radial direction" refers to the radial direction (B direction) based on the rotation axis of the stator core 10 (rotor 150). The terms "radially inner" and "inner diameter side" refer to the direction toward the center of the stator core 10 (B1 direction). The terms "radially outer" and "outer diameter side" refer to the direction toward the outside of the stator core 10 (B2 direction).

[0012] As shown in FIG. 1, the rotating electric machine 200 includes a stator 100 and a rotor 150. The stator 100 and the rotor 150 are each formed in an annular shape. The stator 100 and the rotor 150 face each other. The rotor 150 is disposed radially inward (on the B1 direction side) of the stator 100. The rotor 150 is provided with a plurality of permanent magnets (not shown). That is, the rotating electric machine 200 of this embodiment is configured as an inner rotor type rotating electric machine.

[0013] The stator 100 includes a stator core 10. The stator core 10 is disposed radially opposite the rotor 150. The stator core 10 is provided with a plurality of (e.g., 48) slots 11. Teeth 12 are provided between adjacent slots 11. The stator core 10 is configured, for example, by stacking a plurality of electromagnetic steel plates in the direction of the rotation center axis (Z1 direction and Z2 direction) to allow magnetic flux to pass through. The stator core 10 may be formed by compression molding magnetic powder. The stator core 10 has end faces 10a on both one side (Z1 direction side) and the other side (Z2 direction side) in the axial direction. The stator 100 also includes a stator coil 20.

[0014] Fig. 2 is a perspective view of the stator 100 according to this embodiment. Fig. 3 is a diagram for explaining the configuration of the coil pieces 70 that form the stator coil 20.

[0015] As shown in Fig. 2, the stator coil 20 is wound around the stator core 10. In this embodiment, the stator coil 20 has a plurality of coil pieces 70 (Fig. 3) arranged in each of the plurality of slots 11. In the illustrated example, the stator coil 20 is wound using wave winding, but the winding method is arbitrary.

[0016] In this embodiment, the multiple coil pieces 70 are in the form of so-called segment coils. The multiple coil pieces 70 include first coil pieces 71 having an inverted U-shape when viewed with the Z1 side facing up, and second coil pieces 72 having an inverted U-shape when viewed with the Z2 side facing up. Each of the multiple coil pieces 70 may be in the form of a rectangular conductor wire 77 having a rectangular cross section covered with an insulating coating 78.

[0017] In this embodiment, the flat conductor wire 77 has a uniform rectangular cross section, and the coil pieces 70 are formed by bending. The rectangular cross section of the flat conductor wire 77 is a rectangle, and hereinafter, the long side is also referred to as "flatwise (FW)" and the short side is also referred to as "edgewise (EW)."

[0018] 3, the stator coil 20 is formed by connecting the first coil pieces 71 and the second coil pieces 72 via a connecting tube 90 within the slots 11. That is, the first coil pieces 71 are connected to the Z1 direction side of the connecting tube 90, and the second coil pieces 72 are connected to the Z2 direction side of the connecting tube 90. The method and connection structure of connecting the connecting tube 90 to the first coil pieces 71 or the second coil pieces 72 will be described in detail later.

[0019] Each of the plurality of coil pieces 70 includes a slot insertion portion 21 and transition portions 22 and 23 .

[0020] The slot insertion portion 21 extends in the axial direction (Z direction) and is housed in each of the plurality of slots 11.

[0021] The transition portions 22 connect pairs of the multiple slot-inserted portions 21 of the first coil pieces 71. That is, the transition portions 22 connect the slot-inserted portions 21 housed in different slots 11 (see FIG. 1). The transition portions 22 are formed on the Z1 direction side.

[0022] Similarly, the transition portions 23 connect pairs of the multiple slot insertion portions 21 of the second coil pieces 72. The transition portions 23 are formed on the Z2 direction side.

[0023] In a configuration in which the first coil piece 71 and the second coil piece 72 are connected using such a connecting tube 90, the degree of freedom in wiring is increased compared to when the coil pieces are joined together using welding, and it is also possible to reduce the number of processes and the physical size.

[0024] Fig. 4 is an explanatory diagram showing an example of a method for connecting the connecting pipe 90 to the first coil pieces 71 or the second coil pieces 72. In Fig. 4, only a portion (near the end portions) of the first coil pieces 71 and the second coil pieces 72 is shown for the purpose of explanation.

[0025] The connection pipe 90 is made of a conductor (e.g., a copper pipe) and has a hollow portion with a rectangular cross section. The rectangular cross section is rectangular, but it may also be square. The rectangular cross section may also have corners with slight rounding.

[0026] In the example shown in FIG. 4 , first, the connecting tube 90 is fitted onto the second coil pieces 72 (S41). That is, the tip ends of the slot insertion portions 21 of the second coil pieces 72 are inserted into the hollow portion of the connecting tube 90. The insulating coating 78 is removed from the tip ends of the second coil pieces 72 inserted into the connecting tube 90, exposing the flat conductor wires 77. Next, the first coil pieces 71 are fitted into the connecting tube 90 (S42), thereby connecting the first coil pieces 71 and the second coil pieces 72 via the connecting tube 90 (S43). Similarly, the insulating coating 78 is removed from the tip ends of the first coil pieces 71 inserted into the connecting tube 90, exposing the flat conductor wires 77. Note that when the first coil pieces 71 and the second coil pieces 72 are fitted into the connecting tube 90 in this manner, the tip ends of the first coil pieces 71 and the second coil pieces 72 are axially spaced apart from each other within the hollow portion of the connecting tube 90.

[0027] 4 is merely an example, and is not limited to this. For example, the first coil pieces 71 may be fitted into the connecting pipe 90 first.

[0028] 5 and 6 are cross-sectional views schematically illustrating a connection portion between the connecting tube 90 and the first coil pieces 71 (an example of a first connection portion). Because FIGS. 5 and 6 are explanatory diagrams, the interference between the connecting tube 90 and the first coil pieces 71 is illustrated as if the two components overlap (the overlapping portion is illustrated with matte hatching). The following description will be given in relation to the fitting portion between the connecting tube 90 and the first coil pieces 71, but the same applies to the connection portion between the connecting tube 90 and the second coil pieces 72 (an example of a second connection portion). In reality, there is no overlap, and the connecting tube 72 expands in width in the direction in which the interference occurs by a dimension corresponding to the interference. Therefore, in the following description, the magnitude relationship between the interference in the two directions can be evaluated as follows: The outer circumferential diameter of a reference point in the connecting tube 90 where substantially no deformation due to the interference occurs is defined as the reference value (= design value or ≈ design value). Such a reference point is a point within the hollow portion of the connecting pipe 90 where the tip ends of the first coil pieces 71 and the second coil pieces 72 are spaced apart in the axial direction. Next, the outer diameter (the widened portion due to the interference) of the connecting pipe 90 is measured at a portion where deformation due to interference has occurred. At this time, if the measured value is larger than the reference value, it can be determined that an interference exists, and the magnitude of the interference can be evaluated based on the difference (increment) from the reference value. For example, when comparing the interference along the first direction with the interference along the second direction, the difference from the reference value for each direction is calculated, and by comparing the magnitude of each difference, it can be determined which of the interference along the first direction and the interference along the second direction is larger (or whether they are the same).

[0029] In this embodiment, the connecting pipe 90 receives the slot insertion portions 21 of the first coil pieces 71 in its hollow portion with an interference. That is, the connecting pipe 90 and the first coil pieces 71 are joined with an interference. The tip portions of the first coil pieces 71 that are inserted into the connecting pipe 90 may be roughened by a laser or the like. This promotes metallurgical bonding by adhesion between the connecting pipe 90 and the first coil pieces 71.

[0030] As explained in the section "Problems to be Solved by the Invention," if the insertion load of the first coil pieces 71 into the connecting pipe 90 becomes excessive, buckling deformation of the connecting pipe 90 is likely to occur. The upper limit of the insertion load from the perspective of preventing buckling deformation of the connecting pipe 90 depends on the plate thickness of the connecting pipe 90, and is denoted here as β [N].

[0031] If the thickness of the connecting pipe 90 is reduced in order to reduce the insertion load, the rigidity of the connecting pipe 90 decreases, making it more susceptible to buckling deformation. Also, if the interference is reduced in order to reduce the insertion load, there is a risk that the first coil pieces 71 may become detached from the connecting pipe 90.

[0032] Therefore, in this embodiment, one of the tightening margins in the long side direction and the short side direction of the first coil pieces 71 is set to be larger than the other.

[0033] In the example shown in Fig. 5, the interference in the long side direction of the first coil pieces 71 is larger than the interference in the short side direction. Specifically, the edgewise side of the first coil pieces 71 has an interference with the connecting pipe 90, while the flatwise side has no interference with the connecting pipe 90. Note that in Fig. 5, the parts with interference are shown with matte hatching.

[0034] Hereinafter, such a fitting structure in which the interference on the edgewise side is larger than the interference on the flatwise side will also be referred to as a "fitting structure in which the interference on the EW side is dominant."

[0035] In the example shown in Fig. 6, the interference in the short side direction of the first coil pieces 71 is larger than the interference in the long side direction. Specifically, the flatwise side of the first coil pieces 71 has an interference with the connecting pipe 90, while the edgewise side has no interference with the connecting pipe 90. Note that in Fig. 6, the parts with interference are shown with matte hatching.

[0036] Hereinafter, such a fitting structure in which the interference on the flatwise side is larger than the interference on the edgewise side will also be referred to as a "fitting structure in which the interference on the FW side is dominant."

[0037] Here, the effects of this embodiment will be described with reference to FIGS.

[0038] Fig. 7 is a schematic cross-sectional view of a fitting portion 80' according to a comparative example. Figs. 8 and 9 are diagrams showing the analysis results by comparing the comparative example with this example. Figs. 8 and 9 show, for this example, a fitting structure in which the EW side interference is dominant (in the figure, it is written as "two faces on EW only") and a fitting structure in which the FW side interference is dominant (in the figure, it is written as "two faces on FW only").

[0039] In the analysis of a fitting structure in which the EW side interference is dominant, the interference on the flatwise side was set to 0, and the interference on the edgewise side was set to the standard value α [mm]. In the analysis of a fitting structure in which the FW side interference is dominant, the interference on the edgewise side was set to 0, and the interference on the flatwise side was set to the standard value α [mm]. Figures 8 and 9 show the analysis results for different plate thicknesses of the connecting pipe 90; in Figure 8, the analysis was performed with the connecting pipe 90 plate thickness set to 0.3 [mm], and in Figure 9, the analysis was performed with the connecting pipe 90 plate thickness set to 0.6 [mm].

[0040] In the comparative example, the fitting portion 80' between the first coil piece 71' and the connecting pipe 90' ​​has the same interference on the FW side and the EW side, as shown in Fig. 7. In the analysis, the interference on the flatwise side and the interference on the edgewise side are set to the same standard value α [mm].

[0041] 8 and 9, according to this embodiment, the insertion load can be significantly reduced compared to the comparative example. Specifically, in a fitting structure in which the EW side interference is dominant, the reduction effect is large (plate thickness 0.3: approximately 72% reduction, plate thickness 0.6: 76% reduction). It can be seen that even in a fitting structure in which the FW side interference is dominant, a reduction effect of approximately 50% can be expected (plate thickness 0.3: approximately 50.8% reduction, plate thickness 0.6: 47.5% reduction).

[0042] However, while reducing the insertion load can reduce the possibility of buckling deformation of the connecting pipe 90, if the insertion load is too small, there is a risk that the possibility of the first coil piece 71 coming off the connecting pipe 90 will increase.

[0043] Therefore, in this embodiment, in order to prevent the insertion load from becoming too small, the plate thickness of the connecting pipe 90 on the side with a relatively large clamping margin may be made larger than the plate thickness of the connecting pipe 90 on the side with a relatively small clamping margin.

[0044] That is, in a fitting structure in which the EW side interference is dominant, the plate thickness t1 of the edgewise side connecting pipe 90 may be significantly greater than the plate thickness t2 of the flatwise side connecting pipe 90, as shown in Fig. 5. Similarly, in a fitting structure in which the FW side interference is dominant, the plate thickness t2 of the flatwise side connecting pipe 90 may be significantly greater than the plate thickness t1 of the edgewise side connecting pipe 90, as shown in Fig. 6.

[0045] Hereinafter, making the thickness of the connecting pipe 90 different between the flatwise side and the edgewise side so that the thickness on the side with the interference is relatively larger will also be referred to as "optimizing the thickness of the connecting pipe 90."

[0046] Alternatively, instead of or in addition to optimizing the wall thickness of the connecting pipe 90 described above, the interference itself on the side having the relatively small interference may be adjusted.

[0047] For example, in a fitting structure in which the EW side interference is dominant, the flatwise side interference may be set to a value significantly greater than 0 within a range in which the insertion load is reduced by 20% or more compared to the standard value α [mm]. Similarly, in a fitting structure in which the FW side interference is dominant, the edgewise side interference may be set to a value significantly greater than 0 within a range in which the insertion load is reduced by 20% or more compared to the standard value α [mm].

[0048] Fig. 10 is an analysis result of a fitting structure in which the EW side interference is dominant, and is a diagram showing how the insertion load changes when the flatwise side interference is gradually increased from 0. Fig. 11 is an analysis result of a fitting structure in which the FW side interference is dominant, and is a diagram showing how the insertion load changes when the edgewise side interference is gradually increased from 0.

[0049] In the analysis according to FIG. 10, the interference on the edgewise side is fixed at a standard value α [mm], and in the analysis according to FIG. 11, the interference on the flatwise side is fixed at a standard value α [mm].

[0050] 10 and 11 schematically show the upper limit value β of the insertion load described above.

[0051] As can be seen from Figure 10, in a fitting structure where the EW side interference is dominant, gradually increasing the interference on the flatwise side from 0 also increases the insertion load. In this case, increasing the interference to γ1 allows the insertion load to approach the upper limit value β of the insertion load. Note that the interference γ1 is significantly smaller than the standard value α [mm], and is less than half of the standard value α.

[0052] In this way, even in a fitting structure in which the EW side interference is dominant, the necessary pull-out load can be ensured by providing a slight interference on the flatwise side (within a range significantly smaller than the standard value α [mm]).

[0053] Similarly, as can be seen from Figure 11, in a fitting structure where the FW side interference is dominant, gradually increasing the interference on the edgewise side from 0 also increases the insertion load. In this case, it can be seen that increasing the interference to around γ2 can increase the insertion load to close to the upper limit value β of the insertion load. Note that the interference γ2 is significantly smaller than the standard value α [mm], and is less than half of the standard value α.

[0054] In this way, even in a fitting structure in which the interference on the FW side is dominant, the necessary pull-out load can be ensured by providing a slight interference on the edgewise side (within a range significantly smaller than the standard value α [mm]).

[0055] Although each embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0056] For example, in the above-described embodiment, both the first coil piece 71 and the second coil piece 72 are similarly fitted to the connecting pipe 90 in a manner having the above-described interference, but only one of them may be fitted in a manner having the above-described interference. In this case, the other coil piece and the connecting pipe 90 may be fitted in a manner having an interference different from the above-described manner, or may be joined by another method such as welding (for example, welding before insertion into the slot 11).

[0057] Furthermore, in the above-described embodiment, the connecting pipe 90 is disposed within the slot 11, but it may be disposed axially outward from the axial end face of the stator core 10. [Explanation of symbols]

[0058] 100 Stator (stator for rotating electrical machine), 10 Stator core, 11 Slot, 20 Stator coil, 21 Slot insertion portion, 70 Coil piece, 71 First coil piece (first coil wire), 72 Second coil piece (second coil wire), 90 Connecting tube

Claims

1. a stator core having a plurality of slots arranged in a circumferential direction; a coil wire having a rectangular cross section that passes through the plurality of slots and is wound around the stator core; a connecting pipe having a hollow portion with a rectangular cross section, the coil wire includes a first coil wire connected to one axial side of the connecting pipe and a second coil wire connected to the other axial side of the connecting pipe, the connecting pipe has a first connecting portion on one axial side to which the first coil wire is connected and a second connecting portion on the other axial side to which the second coil wire is connected, At least one of the first connection portion and the second connection portion has an interference, the interference is an interference along a first direction that expands the dimension of the connecting tube in the first direction, of two directions along two orthogonal sides of a rectangle of the coil wire, and the interference along a second direction of the two directions is 0 or smaller than the interference along the first direction.

2. 2. The stator for a rotating electric machine according to claim 1, wherein the interference along the second direction is equal to or less than half of the interference along the first direction.

3. 2. The stator for a rotating electric machine according to claim 1, wherein when the interference along the first direction is α [mm], the interference along the second direction is set so that an insertion load when inserting into the connecting pipe is reduced by 20% or more compared to when the interference along the second direction is α [mm].

4. 4. The stator for a rotating electric machine according to claim 1, wherein, in a cross-sectional view, a side of the connecting pipe whose normal direction is the first direction is thicker than a side of the connecting pipe whose normal direction is the second direction.

Images