Stator of a rotating electrical machine

Abstract

To provide a stator of a rotary electric machine that suppresses stator resonance from occurring due to coil vibration when a rotor rotates.SOLUTION: Due to different thicknesses of slot sheets 26a and 26b arranged between an inner wall of a slot 22 and a straight line portion 30 of a coil segment configuring a coil 14, the fixing strength of the straight line portion 30 fixed in the slot 22 via the slot sheets 26a and 26b becomes different and the rigidity between the straight line portion 30 and a stator core 12 becomes different. Therefore, according to a stator 10 of such a rotary electric machine, the ring stiffness, which is the overall stiffness of the coil 14 arranged in an annular shape, becomes uneven, and the vibration applied to the stator core 12 from each portion of the coil 14 becomes uneven, so that stator resonance is suppressed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a stator of a rotating electrical machine, and more particularly to a technique for reducing noise caused by stator resonance when a rotor rotates. [Background technology]

[0002] A stator for a rotating electric machine is known in which coils are housed in a plurality of slots spaced apart in the circumferential direction of a stator core, and a slot sheet is disposed between each of the coils and the inner wall surfaces of the plurality of slots. Patent Documents 1 and 2 describe examples of such devices. In Patent Document 1, varnish is filled inside and outside the slot sheet (slot paper 21) to fix the coils in the slots. In Patent Document 2, an expandable slot sheet (insulating paper 30) is used, and the slot sheet expands to fix the coils in the slots. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-126178 [Patent Document 2] Japanese Patent Application Publication No. 2018-107921 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in such a rotating electric machine, if vibrations that tend to displace the coils in the slots in the circumferential direction of the stator core occur during rotor rotation, the vibrations are transmitted to the stator core, causing stator resonance, which can vibrate the case that holds the stator, and can worsen NV (Noise, Vibration). In other words, because the coils are arranged in multiple slots to form an annular shape as a whole, and the stiffness of the coils in the circumferential direction of the stator core (hereinafter, this stiffness will be referred to as annular stiffness) is uniform, the vibrations applied to the stator core from the coils in each slot are also uniform, and there is a risk of stator resonance occurring, in which the stator core vibrates together with the coils at a predetermined frequency.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to suppress the occurrence of stator resonance due to vibration of the coil when the rotor rotates. [Means for solving the problem]

[0006] The present invention provides Cylindrical Stator core At equal angular intervals around the axis on the inner surface Spaced apart circumferentially At a certain width Coils are inserted into the multiple slots. Straight section of The coil is accommodated in the slots, and the inner wall surfaces of the slots and the coil Straight section of In a stator of a rotating electric machine in which slot sheets are respectively arranged between the slots, The strength of the fixing between the straight portion of the coil and the inner wall surface of the slot is constant between the slots, and the strength of the fixing between the straight portion of the coil and the inner wall surface of the slot is alternately changed around the axis between the slots. Different The slot sheet is made of a foamed thermosetting resin material having a different thickness between the slots. It is characterized by the following. [Effects of the Invention]

[0007] In the stator of such a rotating electric machine, the inner wall surface of the slot and the coil Straight section of The thickness of the slot sheet disposed between The strength of the fixing between the straight part of the coil and the inner wall surface of the slot is constant between the slots, and the strength of the fixing between the straight part of the coil and the inner wall surface of the slot is constant between the slots. Different The slot sheet is made of foamed thermosetting resin material with different thicknesses between the slots. Therefore, the strength of the coil fixed in the slot through the slot sheet is Alternately around the axis between slots The stiffness between the coil and the stator core is different. Alternately around the axis between slots Therefore, in such a stator for a rotating electric machine, the ring stiffness, which is the stiffness of the entire coil arranged in a ring shape, becomes non-uniform, and the vibrations applied to the stator core from each part of the coil become non-uniform, thereby suppressing stator resonance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view illustrating an example of a stator of a rotating electrical machine to which the present invention is applied; [Figure 2] 2 is a diagram illustrating a state in which a single coil segment is arranged in the stator core of the stator of FIG. 1, and is a development view showing the stator core developed around the axis C as viewed from the inner periphery side. FIG. [Figure 3] FIG. 2 is a diagram showing a part of a cross section of the stator in FIG. 1 during the manufacturing process, showing a state in which slot sheets are disposed in the slots of the stator core and multiple coil segments are inserted. [Figure 4] 2 is a diagram illustrating a vibration model between the coil, stator core, and case in the stator of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A rotating electric machine, sometimes called a rotating machine, is a motor generator used as an electric motor, a generator, or both, such as a permanent magnet three-phase AC synchronous motor. The present invention is applicable to electric vehicle rotating electric machines used as a driving force source for electric vehicles such as electric automobiles and hybrid vehicles, but also to various other rotating electric machines, such as generators for series-type hybrid vehicles and electric motors and generators for non-vehicle applications. The multiple slot sheets arranged in the multiple slots of a stator core may be, for example, multiple types of slot sheets with different thicknesses, as long as the thickness of the slot sheet in at least one slot is different from the thickness of the slot sheet in the other slots. Two types of slot sheets with different thicknesses may be alternately arranged in the circumferential direction, or three or more types of slot sheets with different thicknesses may be used. As the slot sheets, various conventionally used sheets can be used, such as the slot paper and insulating paper described in Patent Documents 1 and 2. [Example]

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings have been appropriately simplified or modified for the purpose of explanation, and the shapes, dimensional ratios, angles, etc. of the various parts are not necessarily drawn accurately.

[0011] FIG. 1 is a perspective view illustrating a schematic configuration of a stator 10 of a rotating electric machine MG to which the present invention is applied. The rotating electric machine MG is a motor generator used as a driving power source for electric vehicles such as hybrid vehicles and electric automobiles, and is a three-phase AC synchronous motor or the like. The rotating electric machine MG includes a cylindrical stator 10 and a rotor (not shown) disposed on the inner periphery of the stator 10, which are rotatable relative to each other about a common center line, i.e., an axis C. The stator 10 includes a cylindrical stator core 12 concentric with the axis C, a coil 14, and a power line 16. The stator core 12 is formed by laminating a number of annular steel plates in an axial direction parallel to the axis C, at a right angle to the axis C. A plurality of teeth 20 are provided on the inner periphery of the stator core 12 at equal angular intervals around the axis C, and are parallel to the axis C. A slot 22, which is a groove-like gap, is formed between adjacent teeth 20 in the circumferential direction around the axis C, and a portion of the coil 14 wound around the tooth 20 is accommodated in the slot 22.

[0012] In this embodiment, the coils 14 are three-phase windings of U-phase, V-phase, and W-phase, and are housed in a large number of slots 22 provided around the entire circumference of the stator core 12 so as to form an annular shape as a whole, with the ends of each coil 14 electrically connected to power lines 16. External terminals 18 are attached to the ends of each of the power lines 16 for connection to an inverter or the like (not shown). In this embodiment, the coils 14 are distributed windings wound across a plurality of teeth 20.

[0013] The coil 14 is formed by connecting a number of coil segments 24 shown in FIG. 2 in a coil shape. FIG. 2 shows one coil segment 24 arranged in a slot 22 formed in the stator core 12, with a slot sheet 26a or 26b pre-installed on the inner wall surface of the slot 22. FIG. 2 is an exploded view of the stator core 12 as viewed from the inner circumferential side (axis C side) of the stator core 12. The coil segment 24 is generally U-shaped, and a pair of parallel straight portions 30 of the U-shape are housed in different slots 22 among the many slots 22 in an orientation that is generally parallel to the axis C. The U-shaped winding portion 32 and the pair of straight portions 30 are arranged in the stator core 12 so as to protrude from the slot 22 on both sides in the axial direction of the stator core 12 (a direction parallel to the axis C, the up-down direction in FIG. 2). In the numerous slots 22 around the axis C, numerous coil segments 24 are arranged consecutively while being offset in the circumferential direction and radial direction around the axis C. Figure 3 is a cross-sectional view of a portion of the stator 10 during the manufacturing process, taken at a cross section perpendicular to the axis C, in which the straight portions 30 of the numerous coil segments 24 are housed so as to overlap in the radial direction within each of the numerous slots 22. In this embodiment, the coil segments 24 are rectangular wires with a rectangular cross section like a long conductor plate, and in Figure 3, the cross sections of the straight portions 30 are shown as rectangular.

[0014] As shown in FIG. 1 , among the straight portions 30 of the many coil segments 24, many protruding portions 34, which are portions of the tip side protruding from the slots 22, are twisted around the axis C, which is the circumferential direction of the stator core 12, and the tip ends 36 of the protruding portions 34 are overlapped and joined to other radially adjacent coil segments 24. That is, the many protruding portions 34 positioned consecutively in the radial direction of the stator core 12 are twisted alternately in opposite directions around the axis C in the radial direction, and the tip ends 36 of pairs of radially adjacent protruding portions 34 are joined to form the coil 14 wound across multiple teeth 20. In FIG. 1 , the innermost protruding portion 34 is twisted clockwise as viewed from above in FIG. 1 , and the twist direction is alternately reversed toward the outer periphery, and the outermost protruding portion 34 (the eighth from the inner periphery in FIG. 1 ) is twisted counterclockwise as viewed from above in FIG. 1 . The surfaces of the coil segments 24 are provided with an insulating coating such as enamel, but the insulating coating is removed from the tip ends 36 of the protruding portions 34, and the tip ends 36 are joined together by welding.

[0015] Two types of insulating slot sheets 26a or 26b are disposed between the inner wall surface of the slot 22 and the straight portions 30 of the numerous coil segments 24 that make up the coil 14. The slot sheets 26a and 26b have the same basic structure except for their thicknesses, and are disposed by being bent into a U-shape along the inner wall surface of the slot 22, as shown in FIG. 3 . In this embodiment, the thick slot sheets 26a and the thin slot sheets 26b are disposed in the slot 22, alternately used around the axis C. Then, with the numerous straight portions 30 inserted inside the slot sheets 26a and 26b, an adhesive such as varnish is filled inside and outside the slot sheets 26a and 26b, thereby fixing the straight portions 30 in the slot 22 via the slot sheets 26a or 26b. In this case, since the slot sheets 26a, 26b have different thicknesses, the fixing strength of the straight portion 30 fixed in the slot 22 via the slot sheet 26a or 26b differs, and the rigidity between the straight portion 30 and the stator core 12 differs. In this case, although it depends on the material of the slot sheets 26a, 26b and the type of adhesive, for example, the rigidity between the straight portion 30 and the stator core 12 is higher in the portion where the thick slot sheet 26a is arranged than in the portion where the thin slot sheet 26b is arranged.

[0016] Furthermore, if the slot sheets 26a, 26b are made of, for example, a foamable thermosetting resin material, they can be heated to foam and expand, thereby fixing the straight portions 30 in the slots 22. In this case, the circumferential widths of the many slots 22 and the widths of the straight portions 30 are constant, and the gaps between them are also constant. Therefore, the thicknesses of the slot sheets 26a, 26b in the product state after the two types of slot sheets 26a, 26b are expanded are approximately the same. However, because the sheet thicknesses in the material state before expansion are different, the expansion pressures when the slot sheets expand to fix the straight portions 30 differ, and the fixing strength of the straight portions 30 to the slots 22, i.e., the rigidity between the straight portions 30 and the stator core 12, changes. Specifically, the expansion pressure is higher in the portion where the thick slot sheets 26a are arranged than in the portion where the thin slot sheets 26b are arranged, and the rigidity between the straight portions 30 and the stator core 12 is higher.

[0017] In the stator 10 of the rotating electric machine MG of this embodiment, the slot sheets 26a, 26b disposed between the inner wall surfaces of the slots 22 and the straight portions 30 of the coil segments 24 constituting the coils 14 have different thicknesses, which results in different fixing strengths of the straight portions 30 fixed within the slots 22 via the slot sheets 26a, 26b, and therefore different rigidities between the straight portions 30 and the stator core 12. Therefore, in the stator 10 of the rotating electric machine MG, the annular rigidity, which is the rigidity of the entire coils 14 disposed in an annular shape, becomes non-uniform, which causes non-uniform vibrations applied to the stator core 12 from each portion of the coils 14, thereby suppressing stator resonance.

[0018] 4, when vibrations occur that cause the straight portions 30 of the coils 14 to displace in the circumferential direction of the stator core 12 during rotation of the rotor, the vibrations are transmitted to the stator core, causing stator resonance, which may cause the case holding the stator 10 to vibrate and worsen NV. In this case, if the thicknesses of the slot sheets 26a, 26b are uneven, the rigidity between the straight portions 30 of each slot 22 and the stator core 12 becomes uneven, which makes the ring rigidity of the entire coil 14 uneven, thereby suppressing stator resonance.

[0019] Although the embodiments of the present invention have been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0020] 10: Stator 12: Stator core 14: Coil 22: Slot 26a, 26b: Slot sheet MG: Rotating electric machine

Claims

[Claim 1] A stator for a rotating electric machine, in which a straight portion of a coil is accommodated in a plurality of slots of a constant width that are spaced apart circumferentially at equal angular intervals around an axis on the inner peripheral surface of a cylindrical stator core, and a slot sheet is disposed between each of the inner wall surfaces of the plurality of slots and the straight portion of the coil, The thickness of the slot sheet disposed in each of the plurality of slots is constant between the slots, the fixing strength between the linear portion of the coil and the inner wall surface of the slot is alternately different between the slots around the axis, and the slot sheet is formed by foaming a foamable thermosetting resin material with a thickness that varies between the slots. A stator for a rotating electric machine characterized by:

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