Stator for rotary electrical machine

Abstract

This stator for a rotary electrical machine comprises: a stator core having a plurality of slots; and a stator coil formed by segment coils, each of which is formed by using a straight-angle wire having a rectangular cross section, is inserted into different slots apart in the circumferential direction of the stator core, and has a pair of insertion parts respectively inserted into the different slots and a connection part that connects the pair of insertion parts to each other. When a slot pitch, which is a pitch of slots into which the pair of insertion parts of the segment coil are inserted, is denoted as Ns and the total number of slots in the stator core is denoted as S, the following relational expression (1) is satisfied.　(1): Ns<S / 4

Description

Rotating electric machine stator

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

[0002] 2. Description of the Related Art In recent years, rotating electrical machines for driving vehicles have become increasingly smaller and have higher output, and some of them have stator windings formed using stator coils made of rectangular wires having a rectangular cross section. The following Patent Document 1 describes a stator for a rotating electric machine in which six or more slot conductors are inserted into one slot, in which jumper wires connecting circular windings at different radial positions cross the slots at at least two or more different slot pitches, and the different slot pitches of the jumper wires are N+1 slot pitch and (N+1)±1 slot pitch, where N is defined as the number of slots per pole, and the stator has a plurality of slot conductor groups each made up of a plurality of winding conductors of the same phase, and the plurality of winding conductors making up the slot conductor group are inserted into a predetermined number Ns of slots lined up continuously in the circumferential direction of the stator core so that the slots and layers are adjacent to each other, and when the number of slots per phase per pole is defined as NSPP and the number of jumper wires per phase at (N+1)±1 slot pitch is defined as 2×NJ, the predetermined number Ns is set to satisfy the equation "Ns = NSPP + NJ".

[0003] For rotating electric machines such as those described in Japanese Patent No. 6513831, rotating electric machines with various output ranges are being considered. In particular, miniaturization of the stator core is being considered for low-output rotating electric machines. In this case, if the number of slots in the stator core is reduced, when attempting to insert a segment coil into the slot, the central angle of the coil end portion of the segment coil becomes relatively large, which reduces the rigidity of the curved portion of the coil end portion (i.e., makes it more susceptible to plastic deformation), making it difficult to insert the segment coil through the coil end portion.

[0004] The technology of the present disclosure provides a stator that can improve the productivity of stator coils even when the number of slots in a stator core using segment coils is reduced.

[0005] A first aspect of the technology disclosed herein is a stator for a rotating electrical machine that includes a stator core having a plurality of slots, and segment coils that are constructed using flat wire with a rectangular cross section and are inserted into different slots spaced apart in the circumferential direction of the stator core, the segment coils having a pair of insertion portions that are inserted into the different slots, respectively, and a connecting portion that connects the pair of insertion portions together, and where Ns is the slot pitch that is the pitch between the slots into which the pair of insertion portions of the segment coils are inserted, and S is the total number of slots in the stator core, the stator satisfies the following relational expression (1): Ns<S / 4 ... (1)

[0006] A second aspect of the technique of the present disclosure is the stator for a rotating electric machine according to the first aspect, in which the slot pitch is the slot pitch in an intermediate layer between the outermost layer and the innermost layer of the stator core.

[0007] A third aspect of the technique of the present disclosure is the stator of the rotating electric machine according to the first aspect, in which, when the number of magnetic poles of the rotor that rotates relative to the stator is P, P≦4.

[0008] A fourth aspect according to the technique of the present disclosure is the stator of the rotating electric machine according to the first aspect, in which the total number of slots S in the stator core is 24.

[0009] According to the technology of the present disclosure, a stator is provided that can improve the productivity of stator coils even when the number of slots in a stator core using segment coils is reduced.

[0010] 1 is a perspective view showing a stator of a rotating electric machine according to an embodiment; FIG. 2 is a perspective view showing a stator of a rotating electric machine according to an embodiment; FIG. 3 is a perspective view showing a part of a stator coil and a stator core provided in the stator of a rotating electric machine according to an embodiment; FIG. 4 is a perspective view showing an enlarged part of the configuration shown in FIG. 2; FIG. 5 is a conceptual diagram showing an example of stator coil wiring according to an embodiment; FIG. 6 is a diagram showing an example of stator coil wiring according to an embodiment; FIG. 7 is a diagram showing an example of stator coil wiring according to an embodiment;

[0011] A stator 10 (hereinafter simply referred to as "stator 10") for a rotating electric machine according to an embodiment will be described below with reference to FIGS. 1A to 5. Note that in each drawing, some reference numerals may be omitted for clarity. As shown in FIGS. 1A and 1B, the stator 10 according to this embodiment includes a stator core 12 and a stator coil 19. The stator 10, together with a rotor (not shown), constitutes a three-phase AC rotating electric machine. Note that in FIGS. 1A and 1B, arrows Z, A, and D indicate the circumferential direction, axial direction, and radial direction of the stator core 12, respectively. Hereinafter, the circumferential direction of the stator core 12 may be simply referred to as the "circumferential direction," the axial direction of the stator core 12 may be simply referred to as the "axial direction," and the radial direction of the stator core 12 may be simply referred to as the "radial direction."

[0012] Here, the stator coil 19 in the stator 10 shown in Fig. 1A is arranged according to the coil wiring shown in Fig. 6, which will be described later. Also, the stator coil 19 in the stator 10 shown in Fig. 1B is arranged according to the coil wiring shown in Fig. 7, which will be described later.

[0013] The stator core 12 is formed into a cylindrical shape by laminating a large number of electromagnetic steel plates. The stator core 12 has a yoke 14, a large number of teeth 16, and a plurality of slots 18. The large number of teeth 16 and the plurality of slots 18 are formed on the inner periphery of the stator core 12, alternately arranged in the circumferential direction. The plurality of slots 18 are open on both axial sides and radially inward.

[0014] As shown in FIG. 2 , the stator coil 19 is composed of a plurality of segment coils 20. The segment coils 20 are formed by shaping flat wire made of copper or the like with a rectangular cross section into a generally U-shape. The segment coils 20 have a pair of slot insertion portions 22 extending parallel to each other, a coil end portion 24 connecting one end of the pair of slot insertion portions 22, and a pair of lead portions 26 extending from the other end of the pair of slot insertion portions 22. The segment coil 20 is covered with an insulating coating except for the tip portions of the pair of lead portions 26. The coil end portion 24 is an example of a "connecting portion" according to the technology disclosed herein. The pair of slot insertion portions 22 are an example of a "pair of insertion portions" according to the technology disclosed herein.

[0015] A pair of slot insertion portions 22 are inserted from one axial side into different slots 18 spaced apart in the circumferential direction of the stator core 12. The coil end portions 24 are disposed outside the slots 18 on one axial side of the stator core 12 and connect one end of each pair of slot insertion portions 22 to each other in the circumferential direction. As shown in Figures 1A and 1B, a large number of segment coils 20 are stacked in multiple layers in the radial direction of the stator core 12 and aligned in an annular shape. A pair of lead portions 26 of each segment coil 20 protrudes from the end face on the other axial side of the stator core 12. These lead portions 26 are twisted and joined to the lead portions 26 of other segment coils 20.

[0016] In the following description, the side of the stator core 12 where the coil end portions 24 of the segment coils 20 are located will be referred to as the turn side, and the side of the stator core 12 where the lead portions 26 of the segment coils 20 are located will be referred to as the welding side. Note that the method of joining the lead portions 26 together is not limited to welding, and other joining means (for example, ultrasonic welding, friction welding, mechanical fastening) may of course be used.

[0017] The segment coils 20 are so-called wave wound, that is, wound continuously around the entire circumference of the stator core 12. In other words, the segment coils 20 are arranged along the circumferential direction of the stator core 12 by wave winding, and the segment coils 20 are electrically connected to each other, thereby forming the stator coil 19.

[0018] As shown in Figure 3, the coil end portion 24 of the segment coil 20 is formed in a generally V- or U-shape when viewed in the radial direction. When viewed in the axial direction as shown in Figure 4, the coil end portion 24 is curved in a bow shape along the circumferential direction. The coil end portion 24 has two curved portions 24A extending along the circumferential direction when viewed in the axial direction, and a crank portion 24B located between and connecting the two curved portions 24A. The crank portion 24B is bent in a crank shape so that the two curved portions 24A are offset radially from each other by approximately the thickness of the rectangular wire.

[0019] 1A and 1B, the multiple segment coils 20 form one layer by sequentially inserting the slot insertion portions 22 into the slots 18 of the stator core 12, shifting the slots 18 one by one in the circumferential direction, to complete a full turn. In this embodiment, three layers of segment coils 20 are formed. The circumferential length of the segment coils 20 in each layer varies slightly depending on the radial position of each layer.

[0020] There is a demand for rotating electric machines with a variety of output power ranges. In particular, in the development of low-output rotating electric machines for compact automobiles and the like, miniaturization of the stator core 12 is being considered. In this case, the number of slots in the stator core 12 may be reduced (for example, to 4 poles and 24 slots). In the case of a compact rotating electric machine, when attempting to insert a segment coil 20 into a slot, the central angle of the coil end portion 24 of the segment coil 20 becomes relatively large, which reduces the rigidity of the curved portion 24A of the coil end portion 24 (i.e., makes it more susceptible to plastic deformation), making it difficult to insert the segment coil 20 through the coil end portion 24.

[0021] FIG. 4 is a conceptual diagram illustrating the curved shape of the coil end portion 24. For ease of explanation, one segment coil 20 is shown inserted into two circumferentially spaced slots 18 of the stator core 12. In reality, however, multiple segment coils are inserted into corresponding slots 18. As shown on the left side of FIG. 4 , if the segment coils 20 are relatively long in the stator core 12 and the slots 18 into which the segment coils 20 are inserted are spaced apart by 90 degrees or more, the rigidity of the curved portion 24A of the coil end portion 24 decreases, making it difficult to insert the segment coils 20. However, after extensive research, the inventors have found that insertion is easier if the angle between the slots 18 into which the segment coils 20 are inserted is less than 90 degrees (for example, 75 degrees), as shown on the right side of FIG. 4 .

[0022] Therefore, in the stator coil 19 according to this embodiment, on the turn side, the slot pitch Ns and the total number of slots S have the following relational expression (1).

[0023] Ns<S / 4...(1)

[0024] Here, the slots 18 are evenly arranged along the circumferential direction of the stator core 12. Therefore, by dividing the total number of slots S by 4, the number of slots arranged every 90 degrees is obtained. The slot pitch Ns is the number of slots 18 spanned by a segment coil 20. That is, it is the number of slots 18 from the slot 18 next to the slot 18 into which one of a pair of slot insertion portions 22 of a segment coil 20 is inserted to the slot 18 into which the other is inserted. Therefore, as shown in the above relational expression (1), by setting the slot pitch Ns to be smaller than the value obtained by dividing the total number of slots S by 4, a decrease in the rigidity of the curved portion 24A of the coil end portion 24 of the segment coil 20 is suppressed.

[0025] As shown in Fig. 5, in the stator coil 19 according to this embodiment, the number of rotor poles P is 4, and the total number of slots S is 24 (i.e., 4 poles, 24 slots). Fig. 5 shows only the wiring of the segment coils 20 corresponding to one phase (e.g., U-phase) of the three-phase AC flowing through the stator coil 19.

[0026] The slot pitch Ns is set to 5. As an example, the same segment coil 20 is inserted in slot number 1 of layer number 2 of the middle layer ML on the turn side and slot number 6 of the outermost layer OL. That is, there are five slots 18, from slot number 2, which is the next slot after slot number 1 in which the segment coil 20 is inserted, to slot number 6 in which the same segment coil 20 is inserted.

[0027] In the stator coil 19 according to this embodiment, the slot pitch Ns is 5 in all of the outermost layer OL on the turn side, the innermost layer IL on the turn side, and the intermediate layer between the outermost layer OL and the innermost layer IL on the turn side, and satisfies the slot pitch Ns = 5 < S / 4 (= 24 / 4 = 6).

[0028] Here, the outermost layer OL is a group of segment coils 20 (i.e., a group of segment coils) arranged at the outermost side in the radial direction in the multiple slots 18 of the stator core 12. The innermost layer IL is a group of segment coils 20 arranged at the innermost side in the radial direction in the multiple slots 18 of the stator core 12. Furthermore, the intermediate layer ML is a group of segment coils 20 arranged between the outermost layer OL and the innermost layer IL.

[0029] In this way, in the stator coil 19 according to this embodiment, the slot pitch Ns is set so as to satisfy the above relational expression (1), and further, the segment coils 20 are arranged.

[0030] (Actions and Effects) As described above, in the stator core 12 according to this embodiment, by setting the slot pitch Ns to satisfy the above-mentioned relational expression (1), deformation of the coil end portions 24 of the segment coils 20 is suppressed, and the work of inserting the segment coils 20 into the stator core 12 is facilitated. As a result, the productivity of the stator core 12 is improved.

[0031] For example, there is a growing demand for a combination of slot and magnetic pole numbers suitable for small rotating electric machines, such as 4-pole, 24-slot configurations, for low-power applications such as light vehicles and compact automobiles. However, as the number of slots decreases, the coil end portions 24 of the segment coils 20 become longer relative to the slot pitch Ns. For example, compared to the combinations of pole and slot numbers of 8-pole, 48-slot configurations or 12-pole, 72-slot configurations seen in conventional high-power applications, the reduced number of slots results in relatively longer coil end portions 24. As a result, when inserting the segment coils 20 into the slots 18, the coil end portions 24 deform significantly in a bow shape along the circumferential direction, making it difficult to insert the segment coils 20 into the slots 18. This can result in reduced productivity of the stator core 12. In this configuration, as described above, the slot pitch Ns has a predetermined relationship with the total number of slots, thereby suppressing deformation of the coil end portions 24 and facilitating the insertion of the segment coils 20. For example, even if the number of slots in a stator core using segment coils is reduced, the work of inserting the segment coils 20 becomes easier, thereby improving the productivity of the stator core 12.

[0032] Furthermore, the stator core 12 according to this embodiment has four magnetic poles. Generally, for rotors with four or fewer magnetic poles, the above-mentioned problem is particularly likely to occur in the corresponding stator core 12. In this configuration, as described above, the slot pitch Ns has a predetermined relationship with the total number of slots, so that deformation of the coil end portions 24 is suppressed even in the stator core 12 corresponding to a rotor with four magnetic poles, making it easier to insert the segment coils 20.

[0033] Furthermore, the stator core 12 according to this embodiment has a total number of slots of 24. Generally, the above-mentioned problem is particularly likely to occur in a stator core 12 having a total number of slots of 24. In this configuration, as described above, the slot pitch Ns has a predetermined relationship with the total number of slots, so that deformation of the coil end portions 24 is suppressed even in a stator core 12 corresponding to a rotor with four magnetic poles, making it easier to insert the segment coils 20.

[0034] In the above embodiment, an example in which the rotor has four magnetic poles has been described, but the technology of the present disclosure is not limited to this. The number of magnetic poles P may be equal to or less than four, and for example, the number of magnetic poles P may be two.

[0035] (Variation 1) In another wiring example of the stator core 12 according to this embodiment, as shown in Figure 6, the slot pitch Ns = 5 in 4 poles and 24 slots. As an example, the same segment coil 20 is inserted in slot number 1 of layer number 3 of the turn-side intermediate layer ML and slot number 6 of layer number 2. The slot pitch Ns = 5 < S / 4 (= 24 / 4 = 6) is satisfied.

[0036] As an example, the same segment coil 20 is inserted into the slot with slot number 2 and the slot with slot number 7 of the outermost layer OL on the turn side, and the slot pitch Ns = 5 < S / 4 (= 24 / 4 = 6) is satisfied.

[0037] As an example, the same segment coil 20 is inserted into the slot with slot number 1 and the slot with slot number 6 of the innermost layer IL on the turn side, and the slot pitch Ns = 5 < S / 4 (= 24 / 4 = 6) is satisfied.

[0038] Thus, in the stator coil 19 according to this modification, the slot pitch Ns is 5 in all of the outermost layer OL on the turn side, the innermost layer IL on the turn side, and the intermediate layer between the outermost layer OL and the innermost layer IL on the turn side. The slot pitch Ns = 5 < S / 4 (= 24 / 4 = 6) is satisfied. This allows the stator core 12 according to this modification to achieve the same effects as those of the above embodiment.

[0039] (Variant 2) In the above embodiment, an example has been described in which the slot pitch Ns satisfies the above relational expression (1) in all of the outermost layer OL on the turn side, the innermost layer IL on the turn side, and the intermediate layer ML between the outermost layer OL and the innermost layer IL on the turn side, but the technology of the present disclosure is not limited to this.

[0040] As an example, in this modification, the intermediate layer ML on the turn side satisfies the above-mentioned relational expression (1), as shown in Fig. 7. In the example shown in Fig. 6, the slot pitch Ns of the intermediate layer ML is set to 5. As an example, the same segment coil 20 is inserted in the slot with slot number 1 in layer No. 3 of the intermediate layer ML on the turn side and in the slot with slot number 6 in layer No. 2.

[0041] On the other hand, the slot pitch Ns of the outermost layer OL and the innermost layer IL is set to 6, which does not satisfy the above relational expression (1). In other words, only the slot pitch Ns of the middle layer ML satisfies the above relational expression (1).

[0042] As described above, in this modification, by setting the slot pitch Ns in the intermediate layer ML to satisfy the above relational expression (1), deformation of the coil end portions 24 of the segment coils 20 is suppressed, and the work of inserting the segment coils 20 into the stator core 12 is facilitated. As a result, the productivity of the stator core 12 is improved.

[0043] In general, the above problem is particularly likely to occur when inserting segment coils 20 into slots 18 in the middle layer ML of the stator core 12. In this configuration, as described above, the slot pitch Ns in the middle layer ML is set to satisfy the above relational expression (1), which makes it easier to insert the segment coils.

[0044] In this embodiment, the segment coils 20 are made of rectangular metal wires, but the stator coils 19 may be made of rectangular metal wires. Also, in this embodiment, the stator core 12 is made of laminated steel plates, but the stator core 12 may be made of at least a powder magnetic core.

[0045] In this embodiment, the stator coil 19 may be wound continuously around the entire circumference of the stator core 12 in a so-called wave winding manner.

[0046] The above-described description and illustrations are a detailed explanation of the parts related to the technology of the present disclosure and are merely an example of the technology of the present disclosure. For example, the above description of the configuration, functions, actions, and effects is an explanation of an example of the configuration, functions, actions, and effects of the parts related to the technology of the present disclosure. Therefore, it goes without saying that unnecessary parts may be deleted, new elements may be added, or replacements may be made to the above-described description and illustrations within the scope of the gist of the technology of the present disclosure. Furthermore, to avoid confusion and facilitate understanding of the parts related to the technology of the present disclosure, the above-described description and illustrations omit explanations of common technical knowledge that do not require particular explanation to enable the implementation of the technology of the present disclosure.

[0047] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

[0048] In addition, the disclosure of Japanese Patent Application No. 2023-124989, filed on July 31, 2023, is incorporated herein by reference in its entirety.

Claims

1. A stator for a rotating electric machine comprising: a stator core having a plurality of slots; and a stator coil formed by segment coils made of flat wire having a rectangular cross section and inserted into different slots spaced apart in the circumferential direction of the stator core, the segment coils having a pair of insertion parts respectively inserted into the different slots and a connecting part connecting the pair of insertion parts, the stator coil satisfying the following relational expression (1) where Ns is the slot pitch, which is the pitch of the slots into which the pair of insertion parts of the segment coil are inserted, and S is the total number of slots in the stator core. Ns<S / 4 ... (1) 2. A stator for a rotating electric machine according to claim 1, wherein the slot pitch is the slot pitch in an intermediate layer between the outermost layer and the innermost layer of the stator core.

3. The stator of a rotating electric machine according to claim 1, wherein, when the number of magnetic poles of a rotor that rotates relative to the stator is P, P≦4.

4. The stator for a rotating electric machine according to claim 1, wherein the total number of slots S in the stator core is 24.

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