Coil for rotating electrical machine and rotating electrical machine

Abstract

The invention provides a coil for a rotary electric machine. A cooling liquid circulation groove is formed in one side surface of the coil. The values of a, b, x, and R are set so as to satisfy the following conditions (1) and (2) in the concave cross-section of the coolant flow groove. B / a < = T1 (1) ((b-a) R + ax) / 2 > = T2 (2) a: the length of a virtual chord (v) connecting the opening end of the concave shape of the concave cross-section by a straight line; b: the length of an 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;

Description

Technical Field

[0001] The present invention relates to a coil for a rotating electric machine and a rotating electric machine. Background Art

[0002] As a rotating electric machine such as an electric motor or a generator, there is a structure in which a rotatable rotor is disposed radially inside a ring-shaped stator. The stator includes a stator core and a coil (coil for a rotating electric 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 respectively formed between a plurality of adjacent teeth in the circumferential direction. The coil passes through the slots disposed on both sides of the teeth and is wound around each tooth.

[0003] In such a rotating electric machine, the coil becomes hot during use, and therefore it is desired to efficiently cool the coil. As a method for efficiently cooling the coil of a rotating electric machine, a technique of causing a coolant to flow around the coil is known (for example, refer to Japanese Patent No. 7139969).

[0004] In the rotating electric machine described in Japanese Patent No. 7139969, the coil (coil for a rotating electric machine) wound around the teeth of the stator core is formed of flat wire. And, a substantially arc-shaped coolant flow passage (groove) is formed on the side surface (side surface facing a direction orthogonal to the axial direction) of the insertion portion of the coil passing through the slot. The coolant introduced from one end side in the axial direction of the stator core flows into the coolant flow passage 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 passage at this time. Summary of the Invention

[0005] In the coil (coil for a rotating electric machine) used in the rotating electric machine described in Japanese Patent No. 7139969, since a substantially arc-shaped coolant flow passage is formed on the side surface of the insertion portion, even if the side surface of the insertion portion of the coil approaches (abuts) the side surface of another coil or the inner wall of the slot, a flow path of the coolant can be reliably ensured. However, it is necessary to machine a concave-shaped groove (coolant flow passage) on the surface (side surface) of the insertion portion of the coil. In this case, sometimes the surface strength of the coil and the flow resistance of the coolant increase due to the shape and size of the concave-shaped groove to be machined. Therefore, in such a coil, it is desired to suppress a decrease in surface strength and, in addition, suppress an increase in the flow resistance of the coolant.

[0006] The solution of the present invention provides a coil for a rotating electric machine and a rotating electric machine capable of maintaining surface strength and suppressing the flow resistance of a coolant.

[0007] A coil for a rotating electric machine according to one embodiment of the present invention is formed of a flat wire having a substantially rectangular cross-section, and a coolant flow groove having a substantially arcuate concave cross-section is formed on at least one side surface in a direction orthogonal to the axial direction. In the concave cross-section, when the length of a virtual chord connecting the open ends of the concave shape of the concave cross-section is set as a and the length of an arc along the inner surface of the concave shape is set as b, b / a is equal to or less than a first specified value T1. Further, when the depth from the virtual chord of the concave shape to the deepest part of the arc is set as x and the radius of the arc of the concave shape is set as 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 specified value T2.

[0008] In the coil for a rotating electric machine according to an embodiment of the present invention, by setting the ratio b / a of the length a of the virtual chord of the concave shape forming the coolant flow groove to the length b of the arc along the inner surface of the concave shape to be equal to or less than the first specified value T1, it is possible to suppress deterioration on the surface during machining of the coolant flow groove. Further, by setting the above-described 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 such that the area inside the concave shape is equal to or greater than the second specified value T2, it is possible to sufficiently suppress the flow resistance of the coolant flowing in the coolant flow groove.

[0009] Alternatively, the flat wire having a substantially rectangular cross-section may be formed by covering an outer surface of a wire with an insulating coating film, and the first specified value T1 is an elongation limit value of the insulating coating film.

[0010] In this case, by setting the ratio b / a to be equal to or less than the first specified value T1, it is possible to prevent the insulating coating film from peeling off from the wire when forming the coolant flow groove by stamping.

[0011] Alternatively, the second specified value T2 may be a value that makes the pressure loss of the coolant flowing inside the concave shape equal to or less than a reference value.

[0012] 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 specified value T2, it is 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 is possible to suppress the loss of power for transporting the coolant, and it is possible to sufficiently cool the coil for a rotating electric machine using the coolant.

[0013] In addition, a rotating electric machine according to another aspect of the present invention includes: a stator having a cylindrical stator core in which a plurality of teeth and a plurality of slots are alternately provided on an inner peripheral portion, and a plurality of rotating electric machine coils 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, and a coolant introduced into the first liquid chamber flows into the second liquid chamber through the plurality of slots. Here, the rotating electric machine coil is formed of a flat wire having a substantially rectangular cross section, and a coolant flow passage groove having a substantially arcuate concave cross section is formed on at least one side surface of an insertion portion of the rotating electric machine coil passing through the slot in a direction orthogonal to the axial direction. The concave cross section is formed such that when the length of a virtual chord connecting the open ends of the concave shape of the concave cross section is set as a and the length of an arc along the inner surface of the concave shape is set as b, b / a is equal to or less than a first specified value T1, and when the depth from the virtual chord of the concave shape to the deepest part of the arc is set as x and the radius of the arc is set as 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 more than a second specified value T2.

[0014] In this case, it may be that the flat wire having a substantially rectangular cross section is formed by covering an insulating coating film on the outer surface of the wire, the first specified value T1 is the elongation limit value of the insulating coating film, and the second specified value T2 is a value that makes the pressure loss of the coolant flowing inside the concave shape equal to or less than a reference value.

[0015] For the rotating electric machine coil according to the aspect of the present invention, the ratio b / a of the length a of the virtual chord of the concave shape forming the coolant flow passage groove to the length b of the arc along the inner surface of the concave shape is set to be equal to or less than a first specified value T1, and the above-mentioned lengths a, 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 are set such that the area inside the concave shape is equal to or more than a second specified value T2. That is, 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 more than a second specified value T2. Therefore, when the rotating electric machine coil according to the aspect of the present invention is adopted, it is possible to maintain the surface strength and suppress the flow resistance of the coolant.

[0016] In addition, the rotating electric machine according to the aspect of the present invention adopting the above-mentioned rotating electric machine coil can also obtain the same effects as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1is a longitudinal sectional view of the rotating electrical machine according to the embodiment.

[0018] Figure 2 is a sectional view of the rotating electrical machine according to the embodiment along Figure 1 section line II-II.

[0019] Figure 3 is a sectional view of the coil for the rotating electrical machine according to the embodiment.

[0020] Figure 4 is a coordinate diagram showing the dimensional relationships of the preferred parts of the coil for the rotating electrical machine. Detailed Embodiment

[0021] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0022] Figure 1 is a longitudinal sectional view of the rotating electrical machine 1 according to the present embodiment.

[0023] The rotating electrical machine 1 according to 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 housing 12. The stator 10 is fixed inside the rotating electrical machine housing 12 by fastening connection based on 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).

[0024] It should be noted that the coil 15 constitutes the coil for the rotating electrical machine according to the present embodiment.

[0025] The rotor 11 has a permanent magnet (not shown) mounted near its outer peripheral surface. Moreover, the rotor 11 is supported by a bushing 16 so as to be integrally rotatable on a rotating shaft 17. When the rotating electrical machine 1 is used as a motor, the rotating shaft 17 becomes an output shaft, and when the rotating electrical machine 1 is used as a generator, the rotating shaft 17 becomes a power input shaft. The rotating shaft 17 and the bushing 16 are rotatably supported by the rotating electrical machine housing 12 via bearings 18.

[0026] In the following description, the direction parallel to the rotation axis 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.

[0027] Annular first side housings 19 and second side housings 20 are disposed on one end side and the other end side in the axial direction of the stator core 14. Main portions of the first side housings 19 and the second side housings 20 are formed by the rotating electrical machine housing 12.

[0028] The first side housing 19 covers, from the outside, one axial end face of the stator core 14 and the exposed portion of the coil 15 protruding from this end face. The first side housing 19 and one axial end face of the stator core 14 together form an annular first liquid chamber 21. An inlet 24 for introducing the coolant 23 into the first liquid chamber 21 is formed in the first side housing 19. The inlet 24 is connected to the circulation circuit 25 of the coolant 23. After 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, it flows into the other end side in the axial direction of the stator core 14 through the inside of the stator core 14.

[0029] The second side housing 20 covers, from the outside, the other axial end face of the stator core 14 and the exposed portion of the coil 15 protruding from this end face. The second side housing 20 and the other axial end face of the stator core 14 together form an annular second liquid chamber 22. 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. An outlet 26 for discharging the coolant 23 in the second liquid chamber 22 to the outside is formed in the second side housing 20. The outlet 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 returns from the outlet 26 to the circulation circuit 25.

[0030] The circulation circuit 25 is connected to the feed pump P midway in the circuit. An exchanger OC that cools the coolant 23 by heat exchange with the outside air is connected to the upstream side of the feed pump P in the circulation circuit 25. The downstream side of the feed pump P is connected to the inlet 24. Moreover, the upstream side of the exchanger OC in the circulation circuit 25 is connected to the outlet 26.

[0031] Figure 2 It is a cross-sectional view taken along the II-II line of the rotating electric machine 1 Figure 1 as shown.

[0032] The stator core 14 is formed, for example, by laminating a plurality of electromagnetic steel sheets in the axial direction. As Figure 2 shown, 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.

[0033] 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 flange portions 30 extending from the radially inner ends of the tooth body 29 to both sides in the circumferential direction.

[0034] A radially inwardly open slot 31 is formed between the circumferentially adjacent teeth 28. The slot 31 is formed by being 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 main body 29 and the side portions of the flange portion 30. The portion of the slot 31 formed by the side portions of the left and right tooth main bodies 29 is substantially set to a fixed width. Moreover, 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 main bodies 29.

[0035] It should be noted that the radially inner opening 40 of each slot 31 is formed by being clamped by the front end portions of the left and right (both sides in the circumferential direction) flange portions 30 of the slot 31. Moreover, each slot 31 axially penetrates the stator core 14.

[0036] The coil 15 is provided with, for example, three phases of U-phase, V-phase, and W-phase. The coil 15 is formed, for example, by connecting a plurality of sector coils to each other. The coil 15 is formed by covering the outer surface of the metal wire 41 with an insulating coating film 42. Moreover, the coil 15 is formed of flat wire. That is, the shape of the cross section of the coil 15 orthogonal to the axial direction is substantially formed into a rectangular shape.

[0037] Each coil 15 axially passes through the slot 31 of the stator core 14 and is wound around the corresponding tooth 28 in this state.

[0038] Hereinafter, the portion of the coil 15 passing through the slot 31 will be referred to as the "insertion portion 15a", and the portion exposed to the outside of the slot 31 and wound back toward the other slot 31 will be referred to as the "winding-back portion 15b".

[0039] As Figure 2 shown, the insertion portions 15a of the coil 15 pass through each slot 31 in multiple stages. The multiple insertion portions 15a passing through the same slot 31 are arranged in a column in the radial direction. In the present embodiment, for example, five insertion portions 15a pass through the same slot 31. However, the number of insertion portions 15a passing through the same slot 31 is not limited thereto and can be arbitrarily set.

[0040] A plurality of insertion portions 15a disposed in respective slots 31 are bundled in a state of being arranged in a line, and their peripheries are covered with a sheet of a foaming insulating member 43. The foaming insulating member 43 can be, for example, a member in which a foaming adhesive is disposed (coated) 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-foaming adhesive is disposed (coated) on the back surface of the base sheet. The foaming insulating member 43 is inserted and disposed together with these insertion portions 15a into the corresponding slots 31 in a state of covering the peripheries of the plurality of insertion portions 15a. The foaming insulating member 43 foams in the corresponding slots 31 by performing a heat treatment or the like thereafter. As a result, a part of the outer surface of the foaming insulating member 43 adheres to the inner wall of the slot 31.

[0041] Even after the insertion portions 15a of the coil 15 and the foaming insulating member 43 are disposed in the slot 31 as described above, a gap for communicating the one end side and the other end side in the axial direction of the stator core 14 can be ensured inside the slot 31. This gap constitutes a coolant passage 44 for allowing the coolant introduced into the first liquid chamber 21 to flow toward the second liquid chamber 22 side. Specifically, the gap constituting the coolant passage 44 is a gap between the inner surface of the foaming insulating member 43 and the insertion portion 15a, a gap between adjacent insertion portions 15a, a gap between the outer surface of the foaming insulating member 43 and the inner wall of the slot 31, and the like. The coolant 23 flowing in the coolant passage 44 in the slot 31 absorbs the heat of the insertion portion 15a of the coil 15.

[0042] Grooves 50 extending along the axial direction of the stator core 14 are formed on the radially inner side surface and the radially outer side surface of each insertion portion 15a disposed in the slot 31. The groove 50 is recessed substantially in an arc shape toward the central region in the width direction of the insertion portion 15a.

[0043] When the plurality of insertion portions 15a and the foaming insulating member 43 are disposed in the slot 31 together, the groove 50 forms a substantially axially extending gap (flow-through gap) between the opposing side surfaces of the insertion portions 15a adjacent in the radial direction and between the side surface of the insertion portion 15a and the inner surface of the foaming insulating member 43.

[0044] It should be noted that, in the present embodiment, the groove 50 formed on the side surface of the coil 15 constitutes a coolant flow groove. Moreover, in the present embodiment, the groove 50 is also continuously formed in the winding portion 15b of the coil 15 with the groove 50 of the insertion portion 15a. Details of the groove 50 will be described in detail later.

[0045] In addition, as Figure 1As shown, the first side housing 19 on one axial end side of the stator core 14 has a first inner peripheral wall 32 facing the first liquid chamber 21. The first inner peripheral wall 32 protrudes cylindrically from the end portion on the radially inner side of the end side wall 33 of the first side housing 19 located at the outer axial end of the first liquid chamber 21 toward one end face in the axial direction of the rotor 11. In the case of the present embodiment, the first inner peripheral wall 32 is composed of a peripheral wall main body portion 12a integrally formed with the rotating electrical machine housing 12 (end side wall 33) and a separate cylindrical member 34 mounted on the outer peripheral surface on the extending end side of the peripheral wall main body portion 12a. The space between the peripheral wall main body portion 12a and the cylindrical member 34 is sealed by an annular sealing member 60.

[0046] However, the first inner peripheral wall 32 may also be integrally formed with the rotating electrical machine housing 12 (end side wall 33) as a whole.

[0047] In addition, the second side housing 20 on the other axial end side of the stator core 14 has a second inner peripheral wall 35 facing the second liquid chamber 22. The second inner peripheral wall 35 protrudes cylindrically from the end portion on the radially inner side of the end side wall 36 of the second side housing 20 located at the outer axial end of the second liquid chamber 22 toward the other end face in the axial direction of the rotor 11. In the case of the present embodiment, the second inner peripheral wall 35 is integrally formed with the rotating electrical machine housing 12 (end side wall 36).

[0048] However, the second inner peripheral wall 35 may also be composed of a peripheral wall main body portion integral with the rotating electrical machine housing 12 (end side wall 36) and a separate cylindrical member, similarly to the first inner peripheral wall 32.

[0049] A cylindrical cover member, i.e., an annular partition wall 37, is provided on the outer peripheral surfaces of the first inner peripheral wall 32 of the first side housing 19 and the second inner peripheral wall 35 of the second side housing 20. The annular partition wall 37 is formed of, for example, a resin material. However, the annular partition wall 37 may also be formed of other raw materials such as a metal material. The annular partition wall 37 has a first end portion 37f facing the inside of the first liquid chamber 21, a second end portion 37s facing the inside of the second liquid chamber 22, and a partition wall main body portion 37b located between the first end portion 37f and the second end portion 37s and facing the inner peripheral surface of the stator core 14. The first end portion 37f is formed to have the same inner diameter as the partition wall main body portion 37b. The middle portion in the extending direction of the second end portion 37s is reduced in diameter stepwise with respect to the partition wall main body portion 37b.

[0050] The inner peripheral surface of the first end portion 37f is fitted to be slidable with 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 sealing member 39f such as an O-ring is fitted in the annular groove 38f. The cylindrical member 34 (the first inner peripheral wall 32) and the first end portion 37f (the annular partition wall 37) are hermetically sealed by the sealing member 39f.

[0051] In the present embodiment, the first end portion 37f constitutes a guiding member inside the first liquid chamber 21 for guiding the coolant in the first liquid chamber 21 to the slot 31 on one axial end side of the stator core 14.

[0052] The inner peripheral surface of the reduced-diameter portion of the second end portion 37s is fitted to be slidable with the outer peripheral surface of the second inner peripheral wall 35. An annular groove 38s is formed on the outer peripheral surface of the second inner peripheral wall 35, and an annular sealing member 39s such as an O-ring is fitted in the annular groove 38s. The second inner peripheral wall 35 and the second end portion 37s (the annular partition wall 37) are hermetically sealed by the sealing member 39s.

[0053] As described above, the annular partition wall 37 hermetically fits the first end portion 37f to the first inner peripheral wall 32 of the first side housing 19 and hermetically fits the second end portion 37s to the second inner peripheral wall 35 of the second side housing 20. The annular partition wall 37 separates the radially inner region of the stator core 14 installed inside the rotating electric machine housing 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 to the radially inner region, the coolant 23 can be prevented from flowing to the outer peripheral surface side of the rotor 11.

[0054] In addition, on the outer peripheral surface of the first end portion 37f of the annular partition wall 37, there is a bulging portion that bulges radially outward from the outer peripheral surface of the partition wall main body portion 37b. The end portion on the stator core 14 side of this bulging portion stands up radially outward stepwise with respect to the outer peripheral surface of the partition wall main body portion 37b. The standing end surface abuts against the end surface on one axial end side of the stator core 14.

[0055] As Figure 2 shown, the outer peripheral surface of the partition wall main body portion 37b of the annular partition wall 37 is maintained in a state of abutting against the inner peripheral surface of the stator core 14. Moreover, 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 small gap so as not to contact the outer peripheral surface of the rotor 11.

[0056] The foamed insulating member 43 housed and arranged in each slot 31 of the stator core 14 together with the plurality of insertion portions 15a of the coil 15 intrudes into the opening 40 on the radially inner side of the slot 31 due to the foaming of the foamed adhesive on the outer surface side caused by heating or the like. The foamed adhesive that has intruded into the opening 40 adheres to the outer peripheral surface of the annular partition wall 37 arranged 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.

[0057] In the rotating electric machine 1 having the above structure, if a current continuously flows through the coil 15 during operation, the coil 15 generates heat and becomes high temperature.

[0058] At this time, the coolant 23 is introduced into the first liquid chamber 21 of the rotating electric machine 1 from the circulation circuit 25 through the inlet 24. The coolant 23 introduced into the first liquid chamber 21 flows in the first liquid chamber 21, thereby cooling the end portion side region (winding portion 15b) of the coil 15 exposed to the outside from one axial end side of the stator core 14. Moreover, the coolant 23 flows from one axial end side toward the other end side in the plurality of slots 31 (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 passing through the slot 31. Moreover, the coolant 23 flowing 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 returns to the circulation circuit 25 through the outlet 26.

[0059] As described above, in the rotating electric machine 1, the stator 10 is always immersed in the coolant 23 in the rotating electric machine housing 12, and in this state, the coolant 23 in the rotating electric machine housing 12 is replaced through the circulation circuit 25. Therefore, the coil 15 of the stator 10 is efficiently cooled by the coolant 23.

[0060] Next, with reference to Figure 3 、 Figure 4 ,details of the groove 50 (coolant flow path) formed on the side surface 15s (side surface facing the direction orthogonal to the axial direction) of each coil 15 will be described.

[0061] Figure 3 is a diagram showing an enlarged cross section of the coil 15. Figure 4 is a coordinate diagram showing the dimensional relationship of the preferred parts of the coil 15.

[0062] As Figure 3 shown, the coil 15 is formed of a flat wire having a substantially rectangular cross section.

[0063] As described above, the coil 15 (flat wire) is uniformly covered with an insulating coating film 42 on the outer surface of the wire 41. The groove 50 is formed in at least one side surface 15s of the coil 15 in a direction orthogonal to the axial direction. In the present embodiment, the same grooves 50 are respectively formed in two side surfaces 15s of the coil 15 facing opposite directions. The substantially arc-shaped concave cross-section of the groove 50 extends along the axial direction of the coil 15.

[0064] The concave cross-section of the groove 50 sets the dimensions of each part in such a way as to satisfy the following formulas (1) and (2) simultaneously.

[0065] b / a ≤ T1…(1)

[0066] ((b - a)R + ax) / 2 ≥ T2…(2)

[0067] a: The length of the virtual chord v that connects the open ends of the concave shape of the concave cross-section

[0068] b: The length of the arc along the inner surface of the concave shape

[0069] x: The depth from the virtual chord v of the concave shape to the deepest part of the arc

[0070] R: The radius of the arc

[0071] T1: The first specified value

[0072] T2: The second specified value

[0073] That is, the concave cross-section of the groove 50 sets the dimensions of a, b, x, and R in such a way that the ratio b / a of the length a of the virtual chord v to the length b of the arc becomes equal to or less than the first specified value T1 and the area inside the concave shape represented by ((b - a)R + ax) / 2 becomes equal to or greater than the second specified value T2.

[0074] The first specified value T1 is the elongation limit value of the insulating coating film 42 covering the outer surface of the wire 41 in the coil 15. That is, the first specified value T1 is set to be the value at which, when the groove 50 is formed by stamping, if the ratio b / a is larger than it, the insulating coating film 42 reaches the extension limit and breaks.

[0075] In addition, the second specified value T2 is the value that makes the pressure loss of the coolant 23 flowing inside the concave shape of the groove 50 equal to or less than the reference value. The reference value of the pressure loss in this case is, for example, the value at which if it is increased to be equal to or greater than it, the loss of the power for transporting the coolant 23 will become equal to or greater than the allowable value, or the value at which if it is increased to be equal to or greater than it, poor cooling of the coil 15 will occur. This reference value can be appropriately set according to the specifications of the rotating electric machine 1.

[0076] It should be noted that Figure 4It is a coordinate diagram showing the test results of the lengths a and b that satisfy Equation (1) and the depths x and radii R that satisfy Equation (2). In Figure 4 a and b are in the area below the dashed line and do not reach the elongation limit value of the insulating coating. Moreover, x and R are in the area above the solid line, and sufficient flow path area can be ensured, and the pressure loss becomes below the reference value.

[0077] As described above, in the coil 15 of the rotating electric machine 1 of the present embodiment, the ratio b / a of the length a of the virtual chord forming the concave shape of the groove 50 (coolant flow groove) and the length b of the arc along the inner surface of the concave shape is set to be below the first specified value T1. Therefore, it is possible to suppress the occurrence of deterioration on the surface during the machining of the groove 50. Moreover, in the coil 15 of the rotating electric 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 arc of the concave shape, and the radius R of the arc of the concave shape are set such that the area inside the concave shape becomes above the second specified value T2. Therefore, it is possible to sufficiently suppress the flow resistance of the coolant 23 flowing in the groove 50.

[0078] 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.

[0079] In addition, in the coil 15 of the rotating electric machine 1 of the present embodiment, the value of the first specified value T1 is set to a value consistent with the elongation limit value of the insulating coating 42 covering the outer surface of the wire 41. Therefore, when this structure is adopted, when forming the groove 50 (coolant flow groove) on the side surface 15s of the insertion portion 15a of the coil 15 passing through the slot 31 of the stator core 14 by stamping, it is possible to prevent the insulating coating 42 from peeling off from the wire 41.

[0080] Furthermore, in the coil 15 of the rotating electric machine 1 of the present embodiment, the value of the second specified value T2 is set to a value such that the pressure loss of the coolant 23 flowing inside the concave shape of the groove 50 becomes below the reference value. Therefore, when this structure is adopted, it is possible to suppress the pressure loss of the coolant 23 flowing inside the concave shape of the groove 50 to below the reference value, suppress the loss of power for transporting the coolant 23, and sufficiently cool the coil 15 with the coolant.

[0081] In addition, the rotating electric machine 1 of the present embodiment forms the groove 50 with the above-described dimensional setting on the side surface 15s of the insertion portion 15a of the coil 15 passing through the slot 31 of the stator core 14. Therefore, it is possible to suppress the peeling of the coil 15 during manufacturing and allow a necessary and sufficient flow rate of the coolant 23 to flow between the plurality of insertion portions 15a accommodated in a close state in the slot 31 and between the insertion portion 15a and the inner surface of the foamed insulating member 43.

[0082] It should be noted that the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from its gist. For example, in the above-described embodiment, the grooves 50 are formed on two side surfaces 15s facing opposite directions of the insertion portion 15a of the coil 15, but the grooves 50 may be formed on at least one of the side surfaces of the coil 15 facing a direction orthogonal to the axial direction. The grooves 50 may also be formed on three or more of the four surfaces around the coil 15.

[0083] In addition, in the above-described embodiment, the coil 15 (coil for rotating electric machine) having the grooves 50 is used for the stator 10 portion of the rotating electric machine 1, but the coil 15 can also be applied to portions other than the stator 10. For example, in a rotating electric machine having a coil winding portion in the rotor portion, it can also be applied to the rotor portion.

Claims

1. A coil for a rotating electric machine, comprising a flat wire having a substantially rectangular cross section, and having a coolant flow groove having a substantially arc-shaped concave cross section formed on at least one side surface facing in a direction perpendicular to the axial direction, wherein: The concave cross section is formed as follows: When the length of a virtual chord connecting the opening ends of the concave shape of the concave cross section with a straight line is set to a and the length of the arc along the inner surface of the concave shape is set to b, b / a becomes less than or equal to a first predetermined value T1, Furthermore, when the depth from the virtual chord of the concave shape to the deepest part of the arc is set to x and the radius of the arc is set to R, the values ​​of a, b, x, and R are set in such a way that the area of ​​the inner side of the concave shape represented by ((ba)R+ax) / 2 becomes greater than the second specified value T2.

2. The coil for a rotating electrical machine according to claim 1, wherein: The flat wire having a substantially rectangular cross section is formed by covering the outer surface of the conductor with an insulating film. The first predetermined value T1 is an elongation limit value of the insulating coating.

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

4. A rotating electrical machine comprising: A stator having a cylindrical stator core having a plurality of teeth and a plurality of slots alternately provided on an inner circumference thereof, and a plurality of rotating electrical machine coils passing through the slots and wound around the teeth; a rotor rotatably disposed radially inward of the stator; A first liquid chamber, which is arranged facing an axial end surface of the stator core; as well as The second liquid chamber is arranged facing the other axial end surface of the stator core, The coolant introduced into the first liquid chamber flows into the second liquid chamber through the plurality of slots, wherein: The rotating electrical machine coil is composed of a flat wire having a substantially rectangular cross section. The insertion portion of the rotating electrical machine coil that passes through the slot has a coolant flow groove having a substantially arc-shaped concave cross section formed on at least one side surface facing a direction perpendicular to the axial direction. The concave cross section is formed as follows: When the length of a virtual chord connecting the opening ends of the concave shape of the concave cross section with a straight line is set to a and the length of the arc along the inner surface of the concave shape is set to b, b / a becomes less than or equal to a first predetermined value T1, Furthermore, when the depth from the virtual chord of the concave shape to the deepest part of the arc is set to x and the radius of the arc is set to R, the values ​​of a, b, x, and R are set in such a way that the area of ​​the inner side of the concave shape represented by ((ba)R+ax) / 2 becomes greater than the second specified value T2.

5. The rotating electrical machine according to claim 4, wherein: The flat wire having a substantially rectangular cross section is formed by covering the outer surface of the conductor with an insulating film. The first predetermined value T1 is the elongation limit value of the insulating film. The second predetermined value T2 is a value that makes the pressure loss of the coolant flowing inside the concave shape equal to or less than a reference value.

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