Coil for rotary electric machines and rotary electric machine

Abstract

To provide a coil for rotary electric machines and a rotary electric machine with which it is possible to maintain surface strength and suppress the circulation resistance of a coolant.SOLUTION: The coil for rotary electric machines has a coolant circulation groove formed on one side surface. The concave cross section of the coolant circulation groove has the values a, b, x, and R set so as to satisfy conditions (1) and (2). (1): b / a≤T1; (2): ((b-a)R+ax) / 2≥T2, where a denotes the length of virtual string v linking concave-shaped opening ends of the concave cross section, b denotes the length of a circular arc extending along the inner surface of the concave shape, x denotes the depth from the virtual string v of the concave shape to the deepest part of the circular arc, R denotes the radius of the circular arc, T1 denotes a first prescribed value, and T2 denotes a second prescribed value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a coil for a rotating electrical machine and a rotating electrical machine.

Background Art

[0002] As a rotating electrical machine such as an electric motor or a generator, there is one in which a rotor is rotatably disposed inside the radial direction of an annular stator. The stator includes a stator core and a coil (coil for a rotating electrical machine) wound around the stator core. The stator core is integrally formed with, for example, a cylindrical back yoke and a plurality of teeth protruding radially inward from the back yoke. Slots are formed between a plurality of adjacent teeth in the circumferential direction. The coil is wound around each tooth through slots disposed on both sides of the teeth.

[0003] In this type of rotating electrical machine, since the coil becomes hot during use, it is desired to efficiently cool the coil. As a method for efficiently cooling the coil of a rotating electrical machine, a method of flowing a coolant around the coil is known (see, for example, Patent Document 1).

[0004] In the rotating electrical machine described in Patent Document 1, a coil (coil for a rotating electrical machine) wound around the teeth of a stator core is formed by a rectangular wire. And, on the side surface (side surface facing the direction orthogonal to the axial direction) of the insertion portion inserted into the slot of the coil, a substantially arc-shaped coolant flow groove (concave groove) is formed. Coolant introduced from one end side in the axial direction of the stator core flows into the coolant flow groove of the insertion portion of the coil, and the coolant flows out to the other end side in the axial direction. The coil is efficiently cooled by the coolant flowing through the coolant flow groove at this time.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the coil (coil for rotating electrical machine) used in the rotating electrical machine described in Patent Document 1, since a substantially arc-shaped coolant flow groove is formed on the side surface of the insertion portion, even if the side surface of the insertion portion of the coil approaches (contacts) the side surface of another coil or the inner wall of the slot, a coolant flow path can be reliably ensured. However, it is necessary to machine a concave groove (coolant flow groove) on the surface (side surface) of the insertion portion of the coil. In this case, depending on the shape and size of the concave groove to be machined, a decrease in the surface strength of the coil and an increase in the flow resistance of the coolant may occur. For this reason, in this type of coil, it is desired to suppress an increase in the flow resistance of the coolant while suppressing a decrease in the surface strength.

[0007] Therefore, the present invention aims to provide a coil for a rotating electrical machine and a rotating electrical machine that can maintain the surface strength and suppress the flow resistance of the coolant.

Means for Solving the Problems

[0008] In order to solve the above problems, the coil for a rotating electrical machine and the rotating electrical machine according to the present invention adopt the following configuration. That is, the coil for a rotating electrical machine according to the present invention is composed of a flat angle line having a substantially rectangular cross section, and at least one side surface facing a direction orthogonal to the axial direction is provided with a coolant flow groove (for example, the concave groove 50 in the embodiment) having a substantially arc-shaped concave cross section. The concave cross section has a length a of a virtual chord (for example, the virtual chord v in the embodiment) that connects the open ends of the concave shape of the concave cross section with a straight line, and an arc length b along the inner surface of the concave shape. When b / a is equal to or less than a first predetermined value T1, and the depth from the virtual chord of the concave shape to the deepest part of the arc is x and the radius of the arc is R, the values of a, b, x, and R are set so that the inner area of the concave shape represented by ((b - a)R + ax) / 2 is equal to or more than a second predetermined value T2.

[0009] For the coil for a rotating electrical machine according to the present invention, by setting the ratio b / a of the length a of the virtual chord forming the coolant flow groove and the length b of the arc along the inner surface of the concave shape to be equal to or less than a first predetermined value T1, it is possible to suppress the occurrence of surface deterioration during the processing of the coolant flow groove. Further, by setting the lengths a and b, the depth x from the virtual chord to the deepest part of the arc of the concave shape, and the radius R of the arc of the concave shape so that the area inside the concave shape is equal to or greater than a second predetermined value T2, it is possible to sufficiently suppress the flow resistance of the coolant flowing through the coolant flow groove.

[0010] The flat angle wire having a substantially rectangular cross-section is formed by applying an insulating coating (for example, the insulating coating 42 in the embodiment) to the outer surface of a conducting wire (for example, the conducting wire 41 in the embodiment), and the first predetermined value T1 is the elongation limit value of the insulating coating.

[0011] In this case, by setting the ratio b / a to be equal to or less than the first predetermined value T1, it is possible to prevent the insulating coating from peeling off from the conducting wire when the coolant flow groove is formed by press molding.

[0012] The second predetermined value T2 is a value at which the pressure loss of the coolant flowing inside the concave shape becomes equal to or less than a reference value.

[0013] In this case, by setting the values of a, b, x, and R such that the area inside the concave shape represented by ((b - a)R + ax) / 2 is equal to or greater than the second predetermined value T2, it becomes possible to suppress the pressure loss of the coolant flowing inside the concave shape to be equal to or less than the reference value. As a result, it becomes possible to sufficiently cool the coil for a rotating electrical machine with the coolant while suppressing the loss of power for feeding the coolant.

[0014] In addition, the rotating electrical machine according to the present invention includes a cylindrical stator core (e.g., stator core 14 in the embodiment) in which a plurality of teeth (e.g., teeth 28 in the embodiment) and a plurality of slots (e.g., slots 31 in the embodiment) are alternately provided on the inner peripheral portion, and a stator (e.g., stator 10 in the embodiment) having a plurality of rotating electrical machine coils (e.g., coil 15 in the embodiment) wound around each of the teeth through the slots, a rotor (e.g., rotor 11 in the embodiment) rotatably disposed radially inside the stator, a first liquid chamber (e.g., first liquid chamber 21 in the embodiment) provided facing one end surface in the axial direction of the stator core, and a second liquid chamber (e.g., second liquid chamber 22 in the embodiment) provided facing the other end surface in the axial direction of the stator core, and is a rotating electrical machine in which the coolant introduced into the first liquid chamber flows into the second liquid chamber through the plurality of slots. The rotating electrical machine coil is formed of a flat wire having a substantially rectangular cross section, and an insertion portion (e.g., insertion portion 15a in the embodiment) inserted into the slot of the rotating electrical machine coil has a coolant flow groove (e.g., concave groove 50 in the embodiment) with a substantially arc-shaped concave cross section formed on at least one side surface facing a direction orthogonal to the axial direction. The concave cross section has a length of a of a virtual chord (e.g., virtual chord v in the embodiment) that connects the open ends of the concave shape of the concave cross section with a straight line, a length of b of an arc along the inner surface of the concave shape, and when b / a is equal to or less than a first predetermined value T1, and a depth from the virtual chord of the concave shape to the deepest part of the arc is x, and a radius of the arc is R, the values of a, b, x, and R are set such that the inner area of the concave shape represented by ((b - a)R + ax) / 2 is equal to or greater than a second predetermined value T2.

[0015] In this case, the flat wire having a substantially rectangular cross section is formed by applying an insulating coating to the outer surface of the conductor, the first predetermined value T1 is the elongation limit value of the insulating coating, and the second predetermined value T2 is desirably a value at which the pressure loss of the coolant flowing inside the concave shape is equal to or less than a reference value.

Advantages of the Invention

[0016] The coil for a rotating electrical machine according to the present invention sets the ratio b / a of the length a of the virtual chord forming the coolant flow groove and the length b of the arc along the inner surface of the concave shape to be equal to or less than a first predetermined value T1, and sets the above lengths a and b, the depth x from the virtual chord to the deepest part of the concave arc, and the radius R of the concave arc so that the area inside the concave shape is equal to or greater than a second predetermined value T2. That is, the values of a, b, x, and R are set so that the area inside the concave shape represented by ((b - a)R + ax) / 2 is equal to or greater than the second predetermined value T2. Therefore, when the coil for a rotating electrical machine according to the present invention is adopted, it is possible to maintain the surface strength and suppress the flow resistance of the coolant. In addition, the rotating electrical machine according to the present invention that adopts the above-described coil for a rotating electrical machine can also obtain the same effects as described above.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a rotating electrical machine 1 of the present embodiment. The rotating electrical machine 1 of the present embodiment includes a stator 10 and a rotor 11. The stator 10 and the rotor 11 are housed inside a rotating electrical machine case 12. The stator 10 is fixed inside the rotating electrical machine case 12 by fastening with bolts 13 or the like. The stator 10 includes a cylindrical stator core 14 and a plurality of coils 15 wound around the stator core 14. The rotor 11 is rotatably disposed radially inside the stator core 14 (stator 10). Note that the coil 15 constitutes the coil for the rotating electrical machine in the present embodiment.

[0019] The rotor 11 has a permanent magnet (not shown) attached near its outer peripheral surface. The rotor 11 is integrally rotatably supported on the rotating shaft 17 via a sleeve 16. The rotating shaft 17 serves as the output shaft when the rotating electrical machine 1 is used as a motor, and serves as the power input shaft when the rotating electrical machine 1 is used as a generator. The rotating shaft 17 and the sleeve 16 are rotatably supported on the rotating electrical machine case 12 via a bearing 18. In the following description, the direction parallel to the rotation axis line C of the rotor 11 is referred to as the axial direction, the rotation direction of the rotor 11 is referred to as the circumferential direction, and the radial direction of the rotor 11 orthogonal to the axial direction and the circumferential direction is referred to as the radial direction.

[0020] Annular first side cases 19 and second side cases 20 are arranged on one end side and the other end side in the axial direction of the stator core 14. The main parts of the first side case 19 and the second side case 20 are formed by the rotating electrical machine case 12.

[0021] The first side case 19 covers from the outside one end face in the axial direction of the stator core 14 and the exposed portion of the coil 15 protruding from the end face. The first side case 19 forms an annular first liquid chamber 21 together with one end face in the axial direction of the stator core 14. An introduction port 24 for introducing the coolant 23 into the first liquid chamber 21 is formed in the first side case 19. The introduction port 24 is connected to a circulation circuit 25 of the coolant 23. The coolant 23 introduced into the first liquid chamber 21 cools the exposed portion of the coil 15 protruding from one end face of the stator core 14, and then flows through the inside of the stator core 14 and into the other end side in the axial direction of the stator core 14.

[0022] The second side case 20 covers the other axial end face of the stator core 14 and the exposed portion of the coil 15 protruding from that end face from the outside. The second side case 20 forms an annular second liquid chamber 22 together with the other axial end face of the stator core 14. The coolant 23 introduced into the first liquid chamber 21 flows into the second liquid chamber 22 through the inside of the stator core 14. The coolant 23 introduced into the second liquid chamber 22 cools the exposed portion of the coil 15 protruding from the other end face of the stator core 14. The second side case 20 is formed with a discharge port 26 for discharging the coolant 23 in the second liquid chamber 22 to the outside. The discharge port 26 is connected to the circulation circuit 25 of the coolant 23. The coolant 23 that has cooled the coil 15 in the second liquid chamber 22 is returned from the discharge port 26 to the circulation circuit 25.

[0023] A feed pump P is connected in the middle of the circulation circuit 25. A heat exchanger OC for cooling the coolant 23 by heat exchange with the outside air is connected upstream of the feed pump P in the circulation circuit 25. The downstream side of the feed pump P is connected to the introduction port 24. Also, the upstream side of the heat exchanger OC in the circulation circuit 25 is connected to the discharge port 26.

[0024] FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 of the rotating electrical machine 1. The stator core 14 is formed, for example, by axially laminating a plurality of electromagnetic steel sheets. As shown in FIG. 2, the stator core 14 is integrally formed with a cylindrical back yoke 27 and a plurality of teeth 28 protruding radially inward from the inner peripheral portion of the back yoke 27. The back yoke 27 is formed such that the center of the cylinder coincides with the rotation axis C.

[0025] The teeth 28 are arranged at intervals in the circumferential direction. The teeth 28 are formed in a T shape when viewed from the axial direction. That is, the teeth 28 are integrally formed with a tooth body 29 protruding radially inward from the inner peripheral portion of the back yoke 27 and a flange portion 30 protruding from the inner radial end of the tooth body 29 to both sides in the circumferential direction.

[0026] Between the teeth 28 adjacent in the circumferential direction, slots 31 opening radially inward are formed. The slots 31 are formed surrounded by the opposing side walls of the adjacent teeth 28 and the inner peripheral wall of the back yoke 27. The side walls of each tooth 28 are formed by the side portions of the tooth body 29 and the flange portion 30. The portion of the slot 31 formed by the side portions of the left and right tooth bodies 29 has a substantially constant width. Also, the width of the portion of the slot 31 formed by the side portions of the left and right flange portions 30 is narrower than the width of the portion formed by the side portions of the left and right tooth bodies 29. Note that the radially inner opening 40 of each slot 31 is formed sandwiched between the tip portions of the flange portions 30 on the left and right (both sides in the circumferential direction) of the slot 31. Also, each slot 31 penetrates the stator core 14 in the axial direction.

[0027] The coils 15 are provided, for example, in three phases of U-phase, V-phase, and W-phase. The coils 15 are configured, for example, by connecting a plurality of segment coils to each other. The outer surface of the metal conductor wire 41 of the coil 15 is covered by an insulating coating 42. Also, the coil 15 is formed of flat wire. That is, the shape of the cross section orthogonal to the axial direction of the coil 15 is formed in a substantially rectangular shape.

[0028] Each coil 15 is inserted axially along the slot 31 of the stator core 14 and is wound around the corresponding tooth 28 in that state. Hereinafter, the portion of the coil 15 inserted into the slot 31 will be referred to as the "insertion portion 15a", and the portion exposed outside the slot 31 and routed in the direction of another slot 31 will be referred to as the "routing portion 15b".

[0029] As shown in FIG. 2, in each slot 31, a plurality of insertion portions 15a of the coil 15 are inserted in multiple stages. The plurality of insertion portions 15a inserted into the same slot 31 are arranged in a row along the radial direction. In the present embodiment, for example, five insertion portions 15a are inserted into the same slot 31. However, the number of insertion portions 15a inserted into the same slot 31 is not limited to this, and can be arbitrarily set.

[0030] In a state where the plurality of insertion portions 15a inserted and arranged in each slot 31 are bundled so as to be arranged side by side in a row, the peripheries thereof are covered by a sheet of the foamable insulating member 43. The foamable insulating member 43 can adopt, for example, a structure in which a foamable adhesive is disposed (applied) on the surface of an electrically insulating base sheet (the surface facing outward in a state of covering the insertion portion 15a), and a non-foamable adhesive is disposed (applied) on the back surface of the base sheet. The foamable insulating member 43 is inserted and arranged in the corresponding slot 31 together with these insertion portions 15a in a state of covering the peripheries of the plurality of insertion portions 15a. The foamable insulating member 43 foams in the corresponding slot 31 by performing heat treatment or the like later. As a result, a part of the outer surface of the foamable insulating member 43 is adhered to the inner wall of the slot 31.

[0031] Even after the insertion portion 15a of the coil 15 and the foamable insulating member 43 are arranged in the slot 31 as described above, a gap is secured inside the slot 31 for communicating one axial end side and the other end side of the stator core 14. This gap constitutes a coolant passage 44 for flowing the coolant introduced into the first liquid chamber 21 toward the second liquid chamber 22 side. Specifically, the gap constituting the coolant passage 44 is, for example, a gap between the inner surface of the foamable insulating member 43 and the insertion portion 15a, a gap between adjacent insertion portions 15a, a gap between the outer surface of the foamable insulating member 43 and the inner wall of the slot 31, and the like. The coolant 23 flowing through the coolant passage 44 in the slot 31 absorbs the heat of the insertion portion 15a of the coil 15.

[0032] On the side faces of each insertion part 15a arranged in the slot 31 that face radially inward and radially outward, concave grooves 50 extending along the axial direction of the stator core 14 are formed. The concave groove 50 is formed to be recessed in a substantially arc shape toward the central region in the width direction of the insertion part 15a. When a plurality of insertion parts 15a are arranged in the slot 31 together with the foamed insulating member 43, the concave groove 50 forms a gap (flow-through gap) extending substantially along the axial direction between the opposing side faces of the insertion parts 15a adjacent in the radial direction and between the side face of the insertion part 15a and the inner surface of the foamed insulating member 43. Note that in this embodiment, the concave groove 50 formed on the side face of the coil 15 constitutes a coolant flow groove. Also, in this embodiment, the concave groove 50 is formed in the lead portion 15b of the coil 15 so as to be continuous with the concave groove 50 of the insertion part 15a. Details of the concave groove 50 will be described in detail later.

[0033] Also, as shown in FIG. 1, the first side case 19 on one end side in the axial direction of the stator core 14 includes a first inner peripheral wall 32 facing the first liquid chamber 21. The first inner peripheral wall 32 projects cylindrically from the radially inner end of the end side wall 33 of the first side case 19 located at the outer end in the axial direction of the first liquid chamber 21 toward one end face in the axial direction of the rotor 11. In the case of this embodiment, the first inner peripheral wall 32 is composed of a peripheral wall main body part 12a integrally formed with the rotating electrical machine case 12 (end side wall 33) and a separate cylindrical member 34 attached to the outer peripheral surface on the extending end side of the peripheral wall main body part 12a. The space between the peripheral wall main body part 12a and the cylindrical member 34 is sealed by an annular seal member 60. However, the first inner peripheral wall 32 may be entirely integrally formed with the rotating electrical machine case 12 (end side wall 33).

[0034] Further, the second side case 20 on the other axial end side of the stator core 14 includes a second inner peripheral wall 35 facing the second liquid chamber 22. The second inner peripheral wall 35 protrudes cylindrically from the radially inner end of the end side wall 36 of the second side case 20 located at the outer axial end of the second liquid chamber 22 toward the other axial end face of the rotor 11. In the case of this embodiment, the second inner peripheral wall 35 is integrally formed with the rotating electrical machine case 12 (end side wall 36). However, the second inner peripheral wall 35 may be configured by a peripheral wall main body portion integral with the rotating electrical machine case 12 (end side wall 36) and a separate cylindrical member, similarly to the first inner peripheral wall 32.

[0035] An annular partition wall 37, which is a cylindrical cover member, is installed on the outer peripheral surfaces of the first inner peripheral wall 32 of the first side case 19 and the second inner peripheral wall 35 of the second side case 20. The annular partition wall 37 is formed of, for example, a resin material. However, the annular partition wall 37 can also be formed of other materials such as a metal material. The annular partition wall 37 has a first end 37f facing the inside of the first liquid chamber 21, a second end 37s facing the inside of the second liquid chamber 22, and a partition wall main body portion 37b located between the first end 37f and the second end 37s and facing the inner peripheral surface of the stator core 14. The first end 37f is formed with the same inner diameter as the partition wall main body portion 37b. The second end 37s has a reduced diameter in a stepped manner with respect to the partition wall main body portion 37b in the middle of the extending direction.

[0036] The inner peripheral surface of the first end 37f is slidably fitted to the outer peripheral surface of the cylindrical member 34 of the first inner peripheral wall 32. An annular groove 38f is formed on the outer peripheral surface of the cylindrical member 34, and an annular seal member 39f such as an O-ring is mounted in the annular groove 38f. The space between the cylindrical member 34 (first inner peripheral wall 32) and the first end 37f (annular partition wall 37) is hermetically sealed by the seal member 39f. In this embodiment, the first end 37f constitutes a guide member that guides the coolant in the first liquid chamber 21 to the slot 31 on one axial end side of the stator core 14 inside the first liquid chamber 21.

[0037] The inner peripheral surface of the reduced-diameter portion of the second end portion 37s is slidably fitted to the outer peripheral surface of the second inner peripheral wall 35. An annular groove 38s is formed in the outer peripheral surface of the second inner peripheral wall 35, and an annular seal member 39s such as an O-ring is mounted in the annular groove 38s. The space between the second inner peripheral wall 35 and the second end portion 37s (annular partition wall 37) is hermetically sealed by the seal member 39s.

[0038] As described above, the first end portion 37f of the annular partition wall 37 is liquid-tightly fitted to the first inner peripheral wall 32 of the first side case 19, and the second end portion 37s is liquid-tightly fitted to the second inner peripheral wall 35 of the second side case 20. The annular partition wall 37 partitions the radially inner region of the stator core 14 attached inside the rotating electric machine case 12 from the outer peripheral surface of the rotor 11. Therefore, even if the coolant 23 leaks from the slot 31 of the stator core 14 into the radially inner region, it is possible to prevent the coolant 23 from flowing into the outer peripheral surface side of the rotor 11.

[0039] In addition, on the outer peripheral surface of the first end portion 37f of the annular partition wall 37, a bulging portion that bulges radially outward from the outer peripheral surface of the partition wall main body portion 37b is provided. The end portion of this bulging portion on the stator core 14 side stands radially outward in a stepped manner with respect to the outer peripheral surface of the partition wall main body portion 37b. This standing end face is in contact with the end face on one axial end side of the stator core 14.

[0040] As shown in FIG. 2, the outer peripheral surface of the partition wall main body portion 37b of the annular partition wall 37 is maintained in contact with the inner peripheral surface of the stator core 14. Further, the inner peripheral surface of the partition wall main body portion 37b of the annular partition wall 37 faces the outer peripheral surface of the rotor 11 with a minute gap therebetween so as not to be in contact with the outer peripheral surface of the rotor 11.

[0041] The foamed insulating member 43 accommodated and disposed in each slot 31 of the stator core 14 together with the plurality of insertion portions 15a of the coil 15 penetrates into the opening 40 on the radially inner side of the slot 31 when the foamed adhesive on the outer surface side foams due to heating or the like. The foamed adhesive that has penetrated into the opening 40 adheres to the outer peripheral surface of the annular partition wall 37 disposed outside the opening 40. As a result, the peripheral wall main body portion 12a of the annular partition wall 37 is adhesively fixed to the foamed insulating member 43 inside the plurality of slots 31 through the opening 40 of the slot 31.

[0042] When a current continuously flows through the coil 15 during operation of the rotating electrical machine 1 configured as described above, the coil 15 generates heat and becomes high in temperature. At this time, the coolant 23 is introduced into the first liquid chamber 21 of the rotating electrical machine 1 from the circulation circuit 25 through the introduction port 24. The coolant 23 introduced into the first liquid chamber 21 cools one end portion side region (the lead portion 15b) of the coil 15 exposed to the outside from one axial end side of the stator core 14 by flowing in the first liquid chamber 21. Further, the coolant 23 flows from one axial end side to the other end side through the plurality of slots 31 (the coolant passage 44 in the slot 31) of the stator core 14 and flows into the second liquid chamber 22. The coolant flowing in the slot 31 cools the insertion portion 15a of the coil 15 inserted in the slot 31. Further, the coolant 23 that has flowed into the second liquid chamber 22 cools the other end portion side region of the coil 15 exposed to the outside from the other axial end side of the stator core 14, and then is returned to the circulation circuit 25 through the discharge port 26.

[0043] As described above, the stator 10 of the rotating electrical machine 1 is always immersed in the coolant 23 in the rotating electrical machine case 12, and the coolant 23 in the rotating electrical machine case 12 is replaced through the circulation circuit 25 in that state. Therefore, the coil 15 of the stator 10 is efficiently cooled by the coolant 23.

[0044] Next, with reference to FIGS. 3 and 4, details of the concave grooves 50 (coolant flow passages) formed on the side surfaces 15s (side surfaces facing in a direction orthogonal to the axial direction) of the respective coils 15 will be described.

[0045] FIG. 3 is an enlarged view showing a cross section of the coil 15. FIG. 4 is a graph showing the dimensional relationships of the desired parts of the coil 15. As shown in FIG. 3, the coil 15 is formed by a flat wire having a substantially rectangular cross section. The coil 15 (flat wire) has an insulating film 42 uniformly adhered to the outer surface of the conducting wire 41 as described above. The concave groove 50 is formed on at least one side surface 15s facing a direction orthogonal to the axial direction of the coil 15. In the present embodiment, similar concave grooves 50 are formed on two side surfaces 15s facing opposite directions of the coil 15. The concave groove 50 has a substantially arc-shaped concave cross section extending along the axial direction of the coil 15.

[0046] The dimensions of each part of the concave cross section of the concave groove 50 are set so as to simultaneously satisfy the following formulas (1) and (2). b / a ≦ T1 …(1) ((b - a)R + ax) / 2 ≧ T2 …(2) a: The length of the virtual chord v connecting the open ends of the concave shape of the concave cross section by a straight line b: The length of the arc along the inner surface of the concave shape x: The depth from the virtual chord v of the concave shape to the deepest part of the arc R: The radius of the arc T1: The first predetermined value T2: The second predetermined value That is, in the concave cross section of the concave groove 50, the ratio b / a of the length a of the virtual chord v and the length b of the arc is equal to or less than the first predetermined value T1, and the dimensions of a, b, x, and R are set so that the inner area of the concave shape represented by ((b - a)R + ax) / 2 is equal to or less than the second predetermined value T2.

[0047] The first predetermined value T1 is the elongation limit value of the insulating film 42 adhered to the outer surface of the conducting wire 41 of the coil 15. That is, when forming the concave groove 50 by press molding, if the ratio b / a becomes larger than this value during the first predetermined value T1, the insulating film 42 reaches the elongation limit and breaks.

[0048] Further, the second predetermined value T2 is a value at which the pressure loss of the coolant 23 flowing inside the concave shape of the concave groove 50 is equal to or less than a reference value. The reference value of the pressure loss in this case is, for example, a value at which the loss of power for feeding the coolant 23 becomes equal to or greater than an allowable value if it becomes larger than this, or a value at which poor cooling of the coil 15 is caused if it becomes larger than this. This reference value can be appropriately set according to the specifications of the rotating electrical machine 1.

[0049] Note that FIG. 4 is a graph showing the test results of plotting the lengths a and b that satisfy equation (1), and the depth x and radius R that satisfy equation (2). In FIG. 4, in the region where a and b are located below the dotted line, the elongation limit value of the insulating film is not reached. Also, in the region where x and R are located above the solid line, a sufficient flow passage area can be ensured, and the pressure loss is equal to or less than the reference value.

[0050] As described above, in the coil 15 of the rotating electrical machine 1 of the present embodiment, the ratio b / a of the length a of the virtual chord of the concave shape forming the concave groove 50 (coolant flow passage groove) and the length b of the arc along the inner surface of the concave shape is set to be equal to or less than the first predetermined value T1. For this reason, it is possible to suppress the occurrence of surface deterioration during the machining of the concave groove 50. Also, in the coil 15 of the rotating electrical machine 1 of the present embodiment, the above lengths a and b, the depth x from the virtual chord v to the deepest part of the concave arc, and the radius R of the concave arc are set such that the area inside the concave shape is equal to or greater than the second predetermined value T2. For this reason, it is possible to sufficiently suppress the flow resistance of the coolant 23 flowing through the concave groove 50. Therefore, when the coil 15 of the present embodiment is adopted, it is possible to maintain the surface strength of the coil 15 and suppress the flow resistance of the coolant 23.

[0051] Also, in the coil 15 of the rotating electrical machine 1 of the present embodiment, the value of the first predetermined value T1 is set to a value that matches the elongation limit value of the insulating film 42 adhered to the outer surface of the conductor 41. For this reason, when this configuration is adopted, it is possible to prevent the insulating film 42 from peeling off from the conductor 41 when the concave groove 50 (coolant flow passage groove) is formed on the side surface 15s of the coil 15 by press molding.

[0052] Furthermore, in the coil 15 of the rotating electrical machine 1 of the present embodiment, the value of the second predetermined value T2 is set to a value such that the pressure loss of the coolant 23 flowing inside the concave shape of the concave groove 50 is equal to or less than the reference value. Therefore, when this configuration is adopted, the pressure loss of the coolant 23 flowing inside the concave shape of the concave groove 50 can be suppressed to be equal to or less than the reference value, and while suppressing the loss of power for feeding the coolant 23, the coil 15 can be sufficiently cooled by the coolant.

[0053] Also, in the rotating electrical machine 1 of the present embodiment, the concave groove 50 with the above-described dimensional setting is formed on the side surface 15s of the insertion portion 15a of the coil 15 inserted into the slot 31 of the stator core 14. Therefore, while suppressing the peeling of the coil 15 during manufacturing, a sufficient flow rate of the coolant 23 can flow between the plurality of insertion portions 15a accommodated and arranged in a proximity state within the slot 31, and between the insertion portion 15a and the inner surface of the foamed insulating member 43.

[0054] Note that the present invention is not limited to the above-described embodiment, and various design changes are possible without departing from the gist thereof. For example, in the above-described embodiment, the concave grooves 50 are formed on the two side surfaces 15s facing the opposite directions of the insertion portion 15a of the coil 15, but the concave grooves 50 may be formed on at least one of the side surfaces facing the direction orthogonal to the axial direction of the coil 15. The concave grooves 50 may be formed on three or more of the four surfaces around the coil 15.

[0055] Also, in the above-described embodiment, the coil 15 (coil for rotating electrical machine) having the above-described concave groove 50 is used in the stator 10 portion of the rotating electrical machine 1, but this coil 15 can also be applied to portions other than the stator 10. For example, in a rotating electrical machine having a coil winding portion in the rotor portion, it can also be applied to the rotor portion.

Explanation of Reference Numerals

[0056] 1... Rotating electrical machine 10... Stator 11... Rotor 14... Stator core 15... Coil (coil for rotating electrical machine) 15a... Insertion part 21... First liquid chamber 22... Second liquid chamber 28... Teeth 31... Slot 41... Conductive wire 42... Insulating film 50... Concave groove (coolant flow groove) v... Virtual chord

Claims

1. A coil for a rotating electrical machine, which is composed of flat wires having a substantially rectangular cross-section, and in which a coolant flow groove having a substantially arc-shaped concave cross-section is formed on at least one side surface facing a direction orthogonal to the axial direction, wherein the concave cross-section is such that, when the length of a virtual chord connecting the open ends of the concave shape of the concave cross-section is a and the length of an arc along the inner surface of the concave shape is b, b / a is equal to or less than a first predetermined value T1, and the values of a, b, x, and R are set such that the area inside the concave shape represented by ((b - a)R + ax) / 2 is equal to or greater than a second predetermined value T2 when the depth from the virtual chord of the concave shape to the deepest part of the arc is x and the radius of the arc is R. The coil for a rotating electrical machine is characterized by this.

2. The flat wire having a substantially rectangular cross-section has an insulating coating adhered to the outer surface of the conductor, and the first predetermined value T1 is the elongation limit value of the insulating coating. The coil for a rotating electrical machine according to claim 1 is characterized by this.

3. The second predetermined value T2 is a value such that the pressure loss of the coolant flowing inside the concave shape is equal to or less than a reference value. The coil for a rotating electrical machine according to claim 1 or 2 is characterized by this.

4. A stator having a cylindrical stator core in which a plurality of teeth and a plurality of slots are alternately provided on the inner peripheral portion, and a plurality of coils for a rotating electrical machine wound around the respective teeth through the slots, a rotor rotatably disposed radially inside the stator, a first liquid chamber provided facing one end surface in the axial direction of the stator core, and a second liquid chamber provided facing the other end surface in the axial direction of the stator core. The rotating electrical machine is provided with these, wherein the coolant introduced into the first liquid chamber flows into the second liquid chamber through the plurality of slots. The rotating electrical machine is such that, the coil for a rotating electrical machine is composed of flat wires having a substantially rectangular cross-section, and in the insertion portion inserted into the slot of the coil for a rotating electrical machine, a coolant flow groove having a substantially arc-shaped concave cross-section is formed on at least one side surface facing a direction orthogonal to the axial direction, wherein the concave cross-section is such that, when the length of a virtual chord connecting the open ends of the concave shape of the concave cross-section is a and the length of an arc along the inner surface of the concave shape is b, b / a is equal to or less than a first predetermined value T1, Moreover, when the depth from the virtual chord of the concave shape to the deepest part of the arc is x and the radius of the arc is R, the values of a, b, x, and R are set such that the area inside the concave shape represented by ((b - a)R + ax) / 2 is equal to or greater than a second predetermined value T2. A rotating electrical machine characterized by this.

5. The flat angle line with a substantially rectangular cross-section is formed by applying an insulating coating to the outer surface of the conductor. The first predetermined value T1 is the elongation limit value of the insulating coating. The second predetermined value T2 is a value such that the pressure loss of the coolant flowing inside the concave shape is equal to or less than a reference value. The rotating electrical machine according to claim 4, characterized by this.

Images