Electrical connection structure

Abstract

The reliability of the connection between the lead wires and power wires is improved while allowing for a certain degree of variation in their relative positions. [Solution] An electrical connection structure is provided between lead wires of each phase drawn from a stator coil for a rotating electric machine and power lines of each phase electrically connected to a power source, wherein the power line has a through hole or recess for receiving the lead wire, and the lead wire is joined to the power line in the through hole or recess.

Description

Technical Field

[0001] The present disclosure relates to an electrical connection structure.

Background Art

[0002] An electrical connection structure between lead wires of each phase drawn from a stator coil for a rotating electrical machine and power lines of each phase electrically connected to a power source is known. In this structure, one of the two lead wires drawn from a coil group of the same phase is bent so as to approach the connection end of the other lead wire at the radially outer end, and the connection ends of the two lead wires are directly welded to the power line.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art as described above, due to variations in the positional relationship between the lead wire and the power line, an undesirable force (for example, a radial tensile force) is likely to occur at the joint between the two. As a result, there is a problem that the reliability of the joint between the lead wire and the power line is reduced.

[0005] Therefore, on one aspect, an object of the present disclosure is to improve the reliability of the joint between the lead wire and the power line while allowing a certain degree of variation in the positional relationship between the lead wire and the power line.

Means for Solving the Problems

[0006] On one aspect, an electrical connection structure between lead wires of each phase drawn from a stator coil for a rotating electrical machine and power lines of each phase electrically connected to a power source, where the power line has a through hole or a recess for receiving the lead wire, An electrical connection structure is provided in which the lead wire is joined to the power line in the through hole or recess. [Effects of the Invention]

[0007] In one respect, this disclosure makes it possible to improve the reliability of the connection between the lead wire and the power wire while allowing for some degree of variation in the relative position of the lead wire and the power wire. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the cross-sectional structure of a rotating electric machine to which the electrical connection structure of this embodiment is applied. [Figure 2] This is a circuit diagram of a Y-connected three-phase coil according to this embodiment. [Figure 3] This is a schematic perspective view showing a portion of the stator on one axial side, and a diagram illustrating the connection between the lead wire and the power wire. [Figure 4] This is a magnified perspective view showing the connection between the lead wire and the power wire. [Figure 5] This is a cross-sectional view illustrating the connection between the lead wire and the power wire. [Figure 6] This is an explanatory diagram illustrating a preferred configuration of a welded joint, and is a schematic cross-sectional view showing the welded joint between one leader line and one power line. [Figure 7] This is an explanatory diagram of a comparative example, a perspective view showing an enlarged view of the connection between the leader wire and the power wire. [Modes for carrying out the invention]

[0009] The following describes each embodiment in detail with reference to the attached drawings. Note that the dimensional ratios in the drawings are merely examples and are not exhaustive. Furthermore, shapes and other details in the drawings may be partially exaggerated for illustrative purposes. Also, for clarity, in some cases, only a portion of parts with the same attribute are assigned reference numerals in the drawings.

[0010] Figure 1 is a schematic cross-sectional view showing the cross-sectional structure of a rotating electric machine 1 to which the electrical connection structure of this embodiment is applied.

[0011] Figure 1 shows the rotation axis 12 of the rotating electric machine 1. In the following description, "axial direction" refers to the direction in which the rotation axis (center of rotation) 12 of the rotating electric machine 1 extends, "outer axial direction" refers to the side away from the axial center C0 of the stator core 211, and "inner axial direction" refers to the side toward the axial center C0 of the stator core 211. Furthermore, "radial direction" refers to the radial direction centered on the rotation axis 12, "outer radial direction" refers to the side away from the rotation axis 12, and "inner radial direction" refers to the side toward the rotation axis 12. In addition, Figure 1 defines the X direction, which is parallel to the axial direction, along with the X1 side and the X2 side. Also in Figure 1, the R direction, which is parallel to the radial direction, along with the R1 side (inner radial direction) and the R2 side (outer radial direction) are defined. In Figures 2 and onward, the X direction and R direction are shown as appropriate.

[0012] The rotating electric machine 1 may be, for example, a motor used for driving vehicles in hybrid vehicles or electric vehicles. However, the rotating electric machine 1 may be used for any other purpose.

[0013] The rotating electric machine 1 is of the inner rotor type, and the stator 21 is provided so as to surround the radially outer side of the rotor 30. The radially outer side of the stator 21 is fixed to the motor housing 10. The stator 21 includes a stator core 211 made of, for example, an annular laminated steel plate of magnetic material, and a plurality of slots 213 are formed on the radially inner side of the stator core 211 around which the stator coil 22 is wound.

[0014] In this embodiment, the stator coil 22 is made of flat rectangular wire. The stator coil 22 may also be formed by a segment coil that includes a U-shape when viewed perpendicular to the axial direction.

[0015] The stator coil 22 includes a slot insertion portion 222, a coil end portion 223, and a lead wire 235 as a power connection end portion. The slot insertion portion 222 is inserted into the slot 213 of the stator core 211. The slot insertion portion 222 is disposed in each slot 213. The coil end portion 223 extends axially outward from the axial end face 2110 of the stator core 211 and connects between the plurality of slot insertion portions 222 located in different slots 213. The lead wire 235 is provided for each phase, and one end thereof is electrically connected to a power source (not shown) via the power line 70.

[0016] The rotor 30 is disposed radially inside the stator 21.

[0017] The rotor 30 includes a rotor core 32, a rotor shaft 34, end plates 35A and 35B, and magnets 62.

[0018] The rotor core 32 is fixed to the radially outer surface of the rotor shaft 34 and rotates integrally with the rotor shaft 34. The rotor core 32 has a shaft hole 320, and the rotor shaft 34 is fitted into the shaft hole 320. The rotor core 32 may be fixed to the rotor shaft 34 by shrink fitting, press fitting, or the like. For example, the rotor core 32 may be coupled to the rotor shaft 34 by a key connection or a spline connection. The rotor shaft 34 is rotatably supported by the motor housing 10 via bearings 14a and 14b. Note that the rotor shaft 34 defines the rotation shaft 12 of the rotating electric machine 1.

[0019] The rotor core 32 is formed of, for example, a laminated steel plate of an annular magnetic material. Magnets 62 are embedded inside the rotor core 32. That is, the rotor core 32 has magnet holes 322 penetrating in the axial direction, and the magnets 62 are inserted and fixed in the magnet holes 322. In a modified example, the rotor core 32 may be formed of a compacted powder body in which magnetic powder is compressed and solidified.

[0020] Although Figure 1 shows a rotating electric machine 1 with a specific structure, the structure of the rotating electric machine 1 is not limited to this specific structure. For example, in Figure 1, the rotor shaft 34 is hollow, but it may be solid. Also, the magnets 62 may be omitted. The rotor may have field windings. Furthermore, it may be a type other than an inner rotor, for example, an outer rotor type.

[0021] Figure 2 is a circuit diagram of a Y-connected three-phase coil according to this embodiment.

[0022] As shown in Figure 2, the stator coil 22 is connected to an external power supply and is configured to receive power (for example, three-phase AC power). The stator coil 22 is configured to generate a magnetic field when power is supplied. The stator coil 22 includes a U-phase coil 230, a V-phase coil 240, and a W-phase coil 250, through which the three-phase (U-phase, V-phase, and W-phase) AC currents flow, respectively.

[0023] The U-phase coil 230 includes U1 coil section 231, U2 coil section 232, U3 coil section 233, and U4 coil section 234, which are connected in parallel to each other. The V-phase coil 240 also includes V1 coil section 241, V2 coil section 242, V3 coil section 243, and V4 coil section 244, which are connected in parallel to each other. The W-phase coil 250 also includes W1 coil section 251, W2 coil section 252, W3 coil section 253, and W4 coil section 254, which are connected in parallel to each other. The U-phase coil 230, V-phase coil 240, and W-phase coil 250 are connected in a Y-connection (star connection). In other words, a so-called "4Y" connection is realized. The AC power related to the U-phase, V-phase, and W-phase, respectively, is input from the power line 70 to the U-phase coil 230, V-phase coil 240, and W-phase coil 250, respectively. The output sides of the U-phase coil 230, V-phase coil 240, and W-phase coil 250 are connected to each other via the neutral wire terminal 262.

[0024] Figure 2 schematically shows the welded joint 299 between the lead wire 235 related to the U-phase coil 230 and the power line 70. The same joining method is used for the V-phase coil 240 and the W-phase coil 250.

[0025] While this explanation focuses on the application of "4Y" wiring, it can also be applied to other wiring configurations such as "2Y" and "6Y" wiring.

[0026] Next, the features of this embodiment will be further explained with reference to Figures 1 and 2, and then to Figure 3 onward. In the following, we will mainly describe the connection method between the lead wire 235 related to one of the three phases (for example, the U-phase coil 230) and the power line 70, but the same applies to the other phases.

[0027] Figure 3 is a schematic perspective view showing a portion of the stator 21 on one axial side, illustrating the connection between the leader wire 235 and the power line 70 (see welded portion 299 in Figure 2). Figure 4 is an enlarged perspective view showing the connection between the leader wire 235 and the power line 70. Figure 5 is a cross-sectional view illustrating the connection between the leader wire 235 and the power line 70, and is a cross-sectional view including both the axial and radial directions.

[0028] In this embodiment, there are four lead wires 235 for each phase, and they are connected to one power line 70. The lead wires 235 are drawn out in the same manner from the end face side of the stator core 211, two at different axial positions. However, in modified examples, they may be drawn out in other ways, for example, the four may be drawn out in a circumferential direction.

[0029] The lead wire 235 may be led out with the longer side of its rectangular cross-section facing axially. The conductor portion 236 of the lead wire 235 is covered with an insulating coating 238. At the tip of the lead wire 235, which is the part that connects to the power line 70, the insulating coating 238 is removed, and the conductor portion 236 is exposed. Hereinafter, the tip of the lead wire 235 where the conductor portion 236 is exposed will also be simply referred to as the "tip portion 237 of the lead wire 235".

[0030] The power lines 70 are provided for each phase and have plate-shaped ends 71. The power lines 70 as a whole may be plate-shaped members (i.e., members commonly referred to as busbars), and may be formed, for example, from a single metal sheet by press molding or the like. The plate-shaped ends 71 ​​may be arranged so that their normal direction (the direction normal to the surface of the plate) faces the radial direction.

[0031] In this embodiment, the power line 70 has a through hole 712 at its end 71. The through hole 712 may be drilled parallel to the normal direction of the end 71 (i.e., radially). The cross-sectional shape (hole shape) of the through hole 712 is a shape corresponding to the cross-sectional shape of the leader line 235, and may be slightly larger than the cross-sectional shape of the leader line 235.

[0032] A lead wire 235 is inserted into the through hole 712. The lead wire 235 is joined to the power line 70 around the through hole 712. That is, the lead wire 235 is joined to the power line 70 at the through hole 712. The joining method is arbitrary, but in this embodiment, it is welding. That is, in this embodiment, the lead wire 235 and the power line 70 are joined via a welded joint 299. In this case, the lead wire 235 may be welded around the entire circumference of the through hole 712, and may also be joined to the peripheral wall of the through hole 712. Such joining may be achieved by laser welding. In this case, by irradiating the tip 237 of the lead wire 235 (the part where the conductor portion 236 is exposed) from the radially outside and around the through hole 712, the tip 237 and the peripheral edge of the through hole 712 can be melted and joined. This efficiently increases the joining area and ensures joining strength.

[0033] The lead wire 235 may penetrate the through hole 712 and its tip may protrude radially outward. That is, the lead wire 235 may extend radially outward beyond the radially outward surface of the end portion 71. In this case, the possibility of the lead wire 235 coming out of the through hole 712 (displacing radially inward and coming out) can be reduced.

[0034] Figure 6 is a schematic diagram illustrating a preferred configuration of the welded joint 299, and is a schematic cross-sectional view showing the welded joint 299 between one leader line 235 and one power line 70.

[0035] In this embodiment, the through hole 712 is a press-formed hole formed in such a manner that burrs 90 are generated. The burrs 90 are generated around the through hole 712 at the end 71 of the power line 70. The burrs 90 may be generated on either the radially outer surface or the radially inner surface of the end 71 of the power line 70, but preferably on the radially outer surface. That is, the drilling (press-forming) of the through hole 712 is preferably achieved by punching from the radially inner surface side in such a manner that burrs are generated on the radially outer surface.

[0036] In this case as well, the welding laser beam is irradiated from the radially outer side toward the tip 237 of the leader wire 235 and around the through hole 712, as shown by arrow R60 in Figure 6, thereby forming the welded portion 299. In this case, the welded portion 299 is formed in a manner that includes the molten portion of the burr 90.

[0037] With the configuration shown in Figure 6, the gap between the through-hole 712 and the lead wire 235 can be made relatively large on the radially inner side (the entrance side during insertion), while the gap between the through-hole 712 and the lead wire 235 can be made relatively small on the radially outer side. This improves the ease of assembly when inserting the lead wire 235 into the through-hole 712, while reducing damage to the insulating coating 238. In other words, the possibility of the welding laser beam passing through the gap between the through-hole 712 and the lead wire 235 and hitting the radially inner portion of the lead wire 235 beyond the tip portion 237 (passing through the through-hole 712) can be effectively reduced. However, if the welding laser beam passes through the gap between the through-hole 712 and the lead wire 235 and hits the radially inner portion of the lead wire 235 beyond the tip portion 237 (the portion where the conductor portion 236 is not exposed), there is a risk of damaging the insulating coating 238 of that portion of the lead wire 235.

[0038] Next, the effects of this embodiment will be further explained with reference to the comparative example shown in Figure 7.

[0039] Figure 7 is an explanatory diagram of a comparative example, and is an enlarged perspective view showing the connection between the leader line 235' and the power line 70'.

[0040] In the power line 70' of the comparative example, a pair of connecting terminals 72' are arranged on one side in the width direction of the main body 71'.

[0041] Incidentally, the power line 70 (and the power line 70' in the comparative example) is joined at one end to the lead wire 235 and at the other end to the power supply side configuration (e.g., inverter). In such a configuration, due to assembly tolerances, dimensional tolerances, etc., forces that would not occur in the nominal state (a state without various tolerances) may act on the welded joint 299'.

[0042] In this respect, in the comparative example, the power line 70' and the leader line 235' are joined radially, so radial tensile forces are more likely to act on the joint (welded area) due to assembly tolerances, dimensional tolerances, etc. That is, if the power line 70' and the leader line 235' are in a positional relationship different from their nominal positional relationship, they are forcibly positioned in the nominal positional relationship using a jig and welding is performed. Then, when they are released from the jig after welding, the power line 70' and the leader line 235' try to return to a positional relationship different from their nominal positional relationship (their original positional relationship), which can cause undesirable tensile forces to act on the joint. When such tensile forces occur, stress concentration occurs at the joint, which may reduce the reliability of the joint.

[0043] In contrast, in this embodiment, the leader wire 235 is inserted into the through hole 712 as described above, so such inconveniences are unlikely to occur. Specifically, in this embodiment, even if the leader wire 235 and the power wire 70 are in a positional relationship different from the nominal positional relationship due to assembly tolerances, dimensional tolerances, etc., it is not necessary to forcibly position them in the nominal positional relationship with a jig. That is, as long as the leader wire 235 is inserted into the through hole 712, the welded joint 299 can be formed, so deviations in the positional relationship (radial positional relationship) between the leader wire 235 and the through hole 712 can be tolerated. Furthermore, by setting an appropriate gap between the leader wire 235 and the through hole 712, even if there are deviations in positional relationships other than radial, such deviations can be tolerated by inserting the leader wire 235 into the through hole 712 at a slight inclination with respect to the normal direction of the end 71. Therefore, according to this embodiment, a decrease in the reliability of the joint due to assembly tolerances, dimensional tolerances, etc. can be effectively prevented.

[0044] Furthermore, in the comparative example, as described above, the pair of connecting terminals 72' are arranged on one side of the main body 71' in the circumferential direction, which makes it easier for stress concentration to occur due to asymmetry. For example, stress concentration may occur on only one of the pair of connecting terminals 72', or a relatively large stress concentration may occur on the connecting portion 73'.

[0045] In contrast, in this embodiment, the power line 70 has a circumferentially symmetrical shape at its end 71. That is, the power line 70 has a symmetrical shape with respect to a straight line passing through the circumferential center of the end 71 (a straight line passing through the plane of the end 71). This reduces the stress concentration that is likely to occur in the comparative example described above. Furthermore, in this embodiment, the four leader lines 235 also have circumferentially symmetrical shapes in pairs. This also reduces stress concentration in the leader lines 235.

[0046] Although each embodiment has been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above.

[0047] For example, in the embodiment described above, the end 71 of the power line 70 is positioned radially outward from the coil end portion 223 to reduce the axial size of the rotating electric machine 1, but the invention is not limited to this configuration. That is, the end 71 may be positioned axially outward from the coil end portion 223. In this case, the end 71 is positioned with its normal direction being axial, and the through hole 712 may be drilled in the axial direction. Also, the tip of the lead wire 235, which extends in the axial direction, may pass through the through hole 712.

[0048] Furthermore, in the above-described embodiment, the leader wire 235 passes through the through hole 712 of the power line 70 and is joined to the power line 70 at the through hole 712, but this is not limited to this. For example, the leader wire 235 may be inserted in a manner that does not pass through the through hole 712 of the power line 70 and joined to the power line 70 by welding. Also, from a similar viewpoint, a recess may be formed at the end 71 instead of the through hole 712 of the power line 70. That is, the through hole 712 may be replaced with a bottomed hole. In this case, the leader wire 235 may be inserted into the recess of the power line 70 and joined to the power line 70 by welding.

[0049] With regard to the embodiments described above, the following is further disclosed.

[0050] [Note 1] An electrical connection structure between the lead wires of each phase drawn from the stator coil of a rotating electric machine and the power lines of each phase that are electrically connected to a power supply, The power line has a through hole or recess for receiving the lead wire, The aforementioned lead wire is joined to the power line in the through hole or recess, forming an electrical connection structure.

[0051] [Note 2] The power line has the through hole at its end, The aforementioned lead wire is joined to the power line around the through hole, according to the electrical connection structure described in Appendix 1. [Note 3] The power line has a plate-like shape at its end. The through hole is drilled perpendicular to the end, as described in Appendix 2, for the electrical connection structure. [Note 4] The through hole is a press-formed hole, and is formed such that a burr is generated around the through hole at the end and on one side of the end surface. The electrical connection structure according to Appendix 2 or 3, wherein the tip of the lead wire protrudes from the surface on one side through the through hole at the end of the power line. [Note 5] The electrical connection structure described in Appendix 4, wherein the lead wire and the power wire are joined by a weld including the molten portion of the burr. [Explanation of Symbols]

[0052] 1 Rotating electric machine, 22 Stator coil, 235 Lead wire, 236 Conductor part (end), 70 Power line, 712 Through hole, 71 End, 299 Welded part, 90 Burr

Claims

1. An electrical connection structure between the lead wires of each phase drawn from the stator coil of a rotating electric machine and the power lines of each phase that are electrically connected to a power supply, The power line has a through hole or recess for receiving the lead wire, The aforementioned lead wire is joined to the power line in the through hole or recess, forming an electrical connection structure.

2. The power line has the through hole at its end, The electrical connection structure according to claim 1, wherein the lead wire is joined to the power line around the through hole.

3. The power line has a plate-like shape at its end. The electrical connection structure according to claim 2, wherein the through hole is drilled perpendicular to the end.

4. The through hole is a press-formed hole, and is formed such that a burr is generated around the through hole at the end and on one side of the end surface. The electrical connection structure according to claim 2 or 3, wherein the tip of the lead wire protrudes from the surface on one side by passing through the through hole at the end of the power line.

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