Insulating cap for stator coil and stator for rotating electric machine

Abstract

Provided is an insulating cap for a stator coil, each of a plurality of slots formed in an inner peripheral surface of a stator core having a bottom coil and an upper coil mounted therein. The insulating cap includes a first insulating cap piece and a second insulating cap piece which are combined with each other. Each of the first insulating cap piece and the second insulating cap piece includes: a bottom coil sidewall part, an upper coil sidewall part located at a position offset from the bottom coil sidewall part in a circumferential direction on the inside in a radial direction of the bottom coil sidewall part; and an inclined wall part connecting the bottom coil sidewall part and the upper coil sidewall part. A coil end part of the bottom coil disposed in a first slot is disposed between the bottom coil sidewall part of the first insulating cap piece and the bottom coil sidewall part of the second insulating cap piece, and a coil end part of the upper coil disposed in a second slot next to the first slot is disposed between the upper coil sidewall part of the first insulating cap piece and the upper coil sidewall part of the second insulating cap piece.

Description

Insulating cap for stator coil and stator for rotating electric machine

[0001] The present disclosure relates to an insulating cap for a stator coil and a stator for a rotating electric machine.

[0002] Patent Document 1 describes a method for electrically connecting the bare conductor ends of the upper coil and the lower coil (bottom coil) mounted in the slots of the stator core of a rotating electric machine with connecting copper bands and insulating the entire connection. In this method, the entire connection, including part of the ground insulation layer of each coil, is enclosed and insulated by a roughly rectangular insulating case pre-filled with insulating filler.

[0003] Japanese Patent Application Laid-Open No. 2001-197697

[0004] When insulating a portion (stator coil jumper connection portion) connecting the ends of a bottom coil and an upper coil mounted in circumferentially adjacent slots in a stator core of a rotating electric machine, it may not be possible to use the rectangular insulating case described in Patent Document 1. Also, with the method of covering the stator coil jumper connection portion with insulating tape, if the worker has low work skills, the worker may not be able to cover the portion with insulating tape properly, and stable insulation performance may not be obtained.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an insulating cap for a stator coil, and a stator for a rotating electric machine equipped with the same, which can properly insulate the connecting portions of the coil ends of the bottom coil and the top coil without relying on the skill of the worker, thereby achieving stable insulating performance.

[0006] In order to achieve the above object, an insulating cap for a stator coil according to at least one embodiment of the present disclosure is an insulating cap for a stator coil applied to a stator coil of a rotating electric machine, wherein a bottom coil and an upper coil arranged radially inward of the bottom coil are fitted in each of a plurality of slots formed in an inner peripheral surface of a stator core of the rotating electric machine, the insulating cap includes a first insulating cap piece and a second insulating cap piece that are combined with each other, each of the first insulating cap piece and the second insulating cap piece includes a bottom coil sidewall portion, an upper coil sidewall portion that is located radially inward of the bottom coil sidewall portion and offset from the bottom coil sidewall portion in the circumferential direction of the rotating electric machine, and an inclined wall portion connecting the bottom coil sidewall portion and the upper coil sidewall portion, and a coil end portion of the bottom coil arranged in a first slot that is one of the plurality of slots is arranged between the bottom coil sidewall portion of the first insulating cap piece and the bottom coil sidewall portion of the second insulating cap piece, The coil end of the upper coil, which is located in a second slot among the plurality of slots that is adjacent to the first slot in the circumferential direction of the rotating electric machine, is arranged between the upper coil side wall portion of the first insulating cap piece and the upper coil side wall portion of the second insulating cap piece.

[0007] In order to achieve the above object, a stator for a rotating electric machine according to at least one embodiment of the present disclosure includes: a stator core; a stator coil; and an insulating cap for the stator coil.

[0008] According to at least one embodiment of the present disclosure, an insulating cap for a stator coil and a stator for a rotating electric machine equipped with the same can be provided, which can properly insulate the connecting portions of the coil ends of the bottom coil and the top coil without relying on the skill of the worker, thereby achieving stable insulating performance.

[0009] 7 is a partially cutaway perspective view showing a schematic configuration of a rotating electric machine 100 according to one embodiment. FIG. 8 is a schematic cross-sectional view showing the configuration of an inner peripheral portion of a stator core 2 in a cross-section perpendicular to the axial direction of the rotating electric machine 100. FIG. 9 is a view for explaining the arrangement of a plurality of insulating caps 30 included in the rotating electric machine 100, as viewed in the axial direction from the turbine side. FIG. 10 is a view showing an example of a cross-section perpendicular to the axial direction of a coil connection portion 26 and an insulating cap 30B. FIG. 11 is a cross-sectional view for explaining details of the configuration shown in FIG. 4. FIG. 12 is a view of the insulating cap 30B as viewed along the axial direction from the opposite side to the stator core 2 in the axial direction. FIG. 13 is a cross-sectional view for explaining details of the configuration shown in FIG. 7. FIG. 14 is a cross-sectional view for explaining a modified example of the insulating cap 30B, showing another example of a cross-section perpendicular to the axial direction of the coil connection portion 26 and the insulating cap 30B.

[0010] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] Fig. 1 is a partially cutaway perspective view showing a schematic configuration of a rotating electrical machine 100 according to an embodiment. For convenience of explanation, Fig. 1 shows the rotating electrical machine 100 with a portion thereof removed.

[0012] Generally, rotating electric machines are roughly classified into three types according to their output (capacity): water-cooled rotating electric machines in which the stator coil is water-cooled and the interior of the machine is cooled with hydrogen gas, hydrogen-cooled rotating electric machines in which the stator coil and the interior of the machine are cooled with hydrogen gas, and air-cooled rotating electric machines in which the stator coil and the interior of the machine are cooled with air. In water-cooled rotating electric machines and hydrogen-cooled rotating electric machines, the interior of the machine is filled with pressurized hydrogen gas.

[0013] The rotating electrical machine (turbine generator) 100 according to this embodiment is filled with hydrogen gas and cooled by the hydrogen gas.

[0014] The rotating electric machine 100 includes a rotor 1 and a stator 4 that is disposed to face the outer peripheral surface of the rotor 1 and that forms a predetermined gap between the rotor 1 and the stator 4. The stator 4 includes a stator core 2 and a stator coil 3.

[0015] In the following description, unless otherwise specified, "axial direction" means the axial direction of the rotating electric machine 100 (the axial direction of the rotor 1, i.e., the axial direction of the stator 4), "radial direction" means the radial direction of the rotating electric machine 100 (the radial direction of the rotor 1, i.e., the radial direction of the stator 4) unless otherwise specified, and "circumferential direction" means the circumferential direction of the rotating electric machine 100 (the circumferential direction of the rotor 1, i.e., the circumferential direction of the stator 4) unless otherwise specified.

[0016] the rotor 1, the stator 4, the crossover wires 13, the lead wires 14, etc., are housed inside the rotating electric machine outer casing 6, which is filled with hydrogen gas; a terminal box 7 connected to the rotating electric machine outer casing 6 and installed below the rotating electric machine outer casing 6; a hydrogen cooler 8 connected to the rotating electric machine outer casing 6 and used to cool the interior of the machine with hydrogen gas; an end bracket 9 that closes the axial end of the rotating electric machine outer casing 6 and houses bearings, etc.; a rocker device 10 that houses current collector tubes and carbon brushes that supply DC current to the coil of the rotor 1; legs 11 to which the rotating electric machine outer casing 6 is fixed; and a current transformer 12 that measures the current that is output from the high-voltage bushing 5 to the outside of the machine.

[0017] The rotating electric machine 100 is connected to, for example, a steam turbine or a gas turbine, and generates electricity by transmitting the rotational energy of the steam turbine or gas turbine to the rotor 1 and rotating the rotor 1 at high speed inside the stator 4.

[0018] The stator 4 is formed by stacking thin silicon steel plates, for example, having a thickness of 1 mm or less (0.35 to 0.50 mm), in the axial direction, the stacked silicon steel plates being electrically insulated from one another, and has a stator core 2 in which a plurality of slots are formed, and a stator coil 3 embedded in the slots, fixed by wedges, and attached to the stator core 2. In other words, the stator core 2 has a plurality of slots in which the stator coils 3 are installed, and is formed by stacking silicon steel plates in the axial direction.

[0019] Next, the slots 19 formed on the inner peripheral surface 20 of the stator core 2 and the stator coil 3 will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view showing the configuration of the inner peripheral part of the stator core 2 in a cross section perpendicular to the axial direction.

[0020] As shown in Figure 2, a plurality of slots 19 are formed in the inner peripheral surface 20 of the stator core 2 at intervals in the circumferential direction. The stator coil 3 includes a bottom coil 3a disposed at the bottom of the slot 19 and an upper coil 3b disposed radially inward of the bottom coil 3a. The bottom coil 3a and the upper coil 3b are electrically connected to each other axially outside the stator core 2 at the axial end of the stator coil 3. The bottom coil 3a and the upper coil 3b embedded in the slots 19 are fixed by wedges 24 disposed on the inner diameter side of the slots 19. In this way, each of the plurality of slots 19 formed in the inner peripheral surface 20 of the stator core 2 is fitted with the bottom coil 3a and the upper coil 3b disposed radially inward of the bottom coil 3a.

[0021] FIG. 3 is a diagram illustrating the arrangement of the insulating caps 30 provided in the rotating electrical machine 100 as viewed in the axial direction from the turbine side.

[0022] 3, the stator 4 (see FIG. 1) of the rotating electric machine 100 includes a plurality of insulating caps 30 arranged in a circumferential direction. The insulating caps 30 are spaced apart in the circumferential direction, and spacers 31 are disposed between adjacent insulating caps 30.

[0023] Each of the insulating caps 30 is configured to cover a coil connection portion connecting the coil end of the bottom coil 3 a and the coil end of the top coil 3 b. The components that make up the insulating cap 30 are made of an insulating material (e.g., thermosetting resin) and may be molded into a cap shape by, for example, BMC (Bulk Molding Compound) molding.

[0024] The insulating caps 30 include insulating cap 30A and insulating cap 30B. The insulating cap 30A is formed in a generally rectangular parallelepiped shape to cover the coil connection portion 25 connecting the coil end of the bottom coil 3a and the coil end of the top coil 3b for the bottom coil 3a and the top coil 3b arranged in the same slot 19. The insulating cap 30B is configured to cover the coil connection portion 26 connecting the coil end 3a1 of the bottom coil 3a and the coil end 3b1 of the top coil 3b for the bottom coil 3a and the top coil 3b arranged in two adjacent slots 19 (see FIG. 2). Here, "the bottom coil 3a and the top coil 3b arranged in two adjacent slots 19" refers to, for example, the bottom coil 3a arranged in a first slot 19a, which is one of the multiple slots 19 shown in FIG. 2, and the top coil 3b arranged in a second slot 19b, which is the slot 19 circumferentially adjacent to the first slot 19a among the multiple slots 19. The coil end of the top coil 3b arranged in the first slot 19a shown in Figure 2 and the coil end of the bottom coil 3a arranged in the second slot 19b are electrically connected via a jumper wire (not shown).

[0025] An example of the configuration of the coil connection portion 26 and the insulating cap 30B will be described below with reference to Figures 4 to 6. Figure 4 is a diagram showing an example of a cross section perpendicular to the axial direction of the coil connection portion 26 and the insulating cap 30B.

[0026] As shown in FIG. 4, the coil connection portion 26 of the stator 4 includes a pair of connection pieces 32, 34 (jumper wire connection pieces) that electrically connect the coil end 3a1 of the bottom coil 3a arranged in the first slot 19a (see FIG. 2) to the coil end 3b1 of the top coil 3b arranged in the second slot 19b (see FIG. 2), which is the slot 19 adjacent to the first slot 19a. Each of the pair of connection pieces 32, 34 is a conductive plate-like member (e.g., copper plate) and has a substantially S-shape in cross section perpendicular to the axial direction. An insulating filler 15 is filled inside the insulating cap 30B around the pair of connection pieces 32, 34 and the coil end portions 3a1, 3b1. In the example shown in the figure, the coil end 3a1 of the bottom coil 3a and the coil end 3b1 of the top coil 3b are sandwiched between a pair of connecting pieces 32, 34, and each of the pair of connecting pieces 32, 34 electrically connects the coil end 3a1 of the bottom coil 3a and the coil end 3b1 of the top coil 3b, but one of the pair of connecting pieces 32, 34 does not have to be provided.

[0027] As shown in Figure 4, in a cross section perpendicular to the axial direction, each of the pair of connection pieces 32, 34 includes a flat bottom coil side connection piece portion 36, a flat upper coil side connection piece portion 38, and an inclined connection piece portion 40.

[0028] In the cross section shown in FIG. 4 , the bottom coil side connection piece 36 of the connection piece 32 is in contact with the coil end 3a1 of the bottom coil 3a placed in the first slot 19a (see FIG. 2 ) and extends radially on a straight line La. The upper coil side connection piece 38 of the connection piece 32 is located radially inward of the bottom coil side connection piece 36 of the connection piece 32 and offset from the bottom coil side connection piece 36 of the connection piece 32 in the circumferential direction. In the cross section shown in FIG. 4 , the upper coil side connection piece 38 of the connection piece 32 is in contact with the coil end 3b1 of the upper coil 3b placed in the second slot 19b (see FIG. 2 ) and extends radially on a straight line Lb. In the cross section shown in FIG. 4 , the inclined connection piece 40 extends in an oblique direction inclined with respect to both the straight lines La and Lb so as to connect the bottom coil side connection piece 36 and the upper coil side connection piece 38. The inclined connection piece portion 40 of the connection piece 32 includes an inclined connection plate portion 40a formed in a flat plate shape, a curved plate portion 40b that curves to connect the inclined connection plate portion 40a of the connection piece 32 to the bottom coil side connection piece portion 36, and a curved plate portion 40c that curves to connect the inclined connection plate portion 40a of the connection piece 32 to the upper coil side connection piece portion 38.

[0029] In the cross section shown in FIG. 4 , the bottom coil side connection piece 36 of the connection piece 34 is in contact with the coil end 3a1 of the bottom coil 3a placed in the first slot 19a (see FIG. 2 ) and extends radially on a straight line Lc. The upper coil side connection piece 38 of the connection piece 34 is located radially inward of the bottom coil side connection piece 36 of the connection piece 34 and offset from the bottom coil side connection piece 36 of the connection piece 34 in the circumferential direction. In the cross section shown in FIG. 4 , the upper coil side connection piece 38 of the connection piece 34 is in contact with the coil end 3b1 of the upper coil 3b placed in the second slot 19b (see FIG. 2 ) and extends radially on a straight line Ld. In the cross section shown in FIG. 4 , the inclined connection piece 40 of the connection piece 34 extends in an inclined direction inclined with respect to both the straight lines Lc and Ld so as to connect the bottom coil side connection piece 36 and the upper coil side connection piece 38 of the connection piece 34. The inclined connection piece portion 40 of the connection piece 34 includes an inclined connection plate portion 40a formed in a flat plate shape, a curved plate portion 40b that curves to connect the inclined connection plate portion 40a of the connection piece 34 and the bottom coil side connection piece portion 36, and a curved plate portion 40c that curves to connect the inclined connection plate portion 40a of the connection piece 34 and the upper coil side connection piece portion 38.

[0030] 4, coil end 3a1 of bottom coil 3a is sandwiched between bottom coil side connecting piece portion 36 of connecting piece 32 and bottom coil side connecting piece portion 36 of connecting piece 34, and coil end 3b1 of top coil 3b is sandwiched between top coil side connecting piece portion 38 of connecting piece 32 and top coil side connecting piece portion 38 of connecting piece 34. In addition, an insulating filler 42 is filled in the space surrounded by the pair of connecting pieces 32, 34, coil end 3a1 of bottom coil 3a, and coil end 3b1 of top coil 3b.

[0031] As shown in Fig. 4, the insulating cap 30B includes a pair of insulating cap pieces 30B1 and 30B2 that are fitted together. The insulating cap pieces 30B1 and 30B2 are molded using the same mold and are formed to have the same shape and dimensions. In the cross section shown in Fig. 4, the insulating cap pieces 30B1 and 30B2 are fitted together while being arranged rotationally symmetrically at 180° about a predetermined axis C.

[0032] As shown in FIG. 4, each of the pair of insulating cap pieces 30B1, 30B2 includes a main wall 43, an inner diameter side end wall 50 and an outer diameter side end wall 52.

[0033] The main wall 43 of the insulating cap piece 30B1 and the main wall 43 of the insulating cap piece 30B2 are arranged facing each other, and a pair of connecting pieces 32, 34, the coil end 3a1 of the bottom coil 3a, and the coil end 3b1 of the upper coil 3b, etc. are arranged between the main wall 43 of the insulating cap piece 30B1 and the main wall 43 of the insulating cap piece 30B2.

[0034] Each of the main walls 43 of the insulating cap piece 30B1 and the insulating cap piece 30B2 includes a bottom coil side wall portion 44, an upper coil side wall portion 46, and an inclined wall portion 48. The upper coil side wall portion 46 of the insulating cap piece 30B1 is located radially inward of the bottom coil side wall portion 44 of the insulating cap piece 30B1 and is offset from the bottom coil side wall portion 44 of the insulating cap piece 30B1 in the circumferential direction, and the inclined wall portion 48 of the insulating cap piece 30B1 connects the bottom coil side wall portion 44 of the insulating cap piece 30B1 and the upper coil side wall portion 46 of the insulating cap piece 30B1. The upper coil side wall portion 46 of the insulating cap piece 30B2 is located radially inward of the bottom coil side wall portion 44 of the insulating cap piece 30B2 and is offset circumferentially from the bottom coil side wall portion 44 of the insulating cap piece 30B2, and the inclined wall portion 48 of the insulating cap piece 30B2 connects the bottom coil side wall portion 44 of the insulating cap piece 30B2 and the upper coil side wall portion 46 of the insulating cap piece 30B1.

[0035] The bottom coil side wall portion 44 and the upper coil side wall portion 46 of the insulating cap piece 30B1 are each formed in a flat plate shape, and the bottom coil side wall portion 44 and the upper coil side wall portion 46 of the insulating cap piece 30B2 are each formed in a flat plate shape. Between the bottom coil side wall portion 44 of the insulating cap piece 30B1 and the bottom coil side wall portion 44 of the insulating cap piece 30B2 are arranged the coil end portion 3a1 of the bottom coil 3a arranged in the first slot 19a (see FIG. 2 ), the bottom coil side connection piece portion 36 of the connection piece 32, and the bottom coil side connection piece portion 36 of the connection piece 34. Between the upper coil side wall portion 46 of the insulating cap piece 30B1 and the upper coil side wall portion 46 of the insulating cap piece 30B2, the coil end portion 3b1 of the upper coil 3b arranged in the second slot 19b (see FIG. 2), the upper coil side connecting piece portion 38 of the connecting piece 32, and the upper coil side connecting piece portion 38 of the connecting piece 34 are arranged. Between the inclined wall portion 48 of the insulating cap piece 30B1 and the inclined wall portion 48 of the insulating cap piece 30B2, the inclined connecting piece portion 40 of the connecting piece 32 and the inclined connecting piece portion 40 of the connecting piece 34 are arranged.

[0036] The bottom coil side wall portion 44 of the insulating cap piece 30B1 and the bottom coil side wall portion 44 of the insulating cap piece 30B2 are arranged in parallel, and in the cross section shown in Fig. 4, the bottom coil side wall portion 44 of the insulating cap piece 30B1 and the bottom coil side wall portion 44 of the insulating cap piece 30B2 each extend linearly along the radial direction. The upper coil side wall portion 46 of the insulating cap piece 30B1 and the upper coil side wall portion 46 of the insulating cap piece 30B2 are arranged in parallel, and in the cross section shown in Fig. 4, the upper coil side wall portion 46 of the insulating cap piece 30B1 and the upper coil side wall portion 46 of the insulating cap piece 30B2 each extend linearly along the radial direction. The inclined wall portion 48 of insulating cap piece 30B1 and the inclined wall portion 48 of insulating cap piece 30B2 are arranged parallel to each other, and in the cross section shown in Figure 4, the inclined wall portion 48 of insulating cap piece 30B1 extends in an inclined direction inclined with respect to both the direction in which the bottom coil side wall portion 44 of insulating cap piece 30B1 extends and the direction in which the upper coil side wall portion 46 of insulating cap piece 30B1 extends, so as to connect the bottom coil side wall portion 44 of insulating cap piece 30B1 and the upper coil side wall portion 46 of insulating cap piece 30B1.

[0037] The inclined wall portion 48 includes an inclined plate portion 48a formed in a flat plate shape, a curved wall portion 48b curved to connect the inclined plate portion 48a and the bottom coil side wall portion 44, and a curved wall portion 48c curved to connect the inclined plate portion 48a and the upper coil side wall portion 46.

[0038] In the cross section shown in Figure 4, the bottom coil side wall portion 44 of the insulating cap piece 30B1 extends on a straight line L1, and the upper coil side wall portion 46 of the insulating cap piece 30B1 extends on a straight line L2 parallel to the straight line L1. Also, in the cross section shown in Figure 4, the bottom coil side wall portion 44 of the insulating cap piece 30B2 extends on a straight line L3 parallel to the straight line L1, and the upper coil side wall portion 46 of the insulating cap piece 30B2 extends on a straight line L4 parallel to the straight line L3. That is, the bottom coil side wall portion 44 of the insulating cap piece 30B1, the upper coil side wall portion 46 of the insulating cap piece 30B1, the bottom coil side wall portion 44 of the insulating cap piece 30B2, and the upper coil side wall portion 46 of the insulating cap piece 30B2 are arranged in parallel.

[0039] The insulating cap piece 30B1 and the connection piece 32 are arranged facing each other with the insulating filler 15 in between, and in the area of ​​the insulating cap piece 30B1 facing the connection piece 32, the distance d1 between the bottom coil side wall portion 44 of the insulating cap piece 30B1 and the bottom coil side connection piece portion 36 of the connection piece 32 becomes smaller as it moves radially outward.

[0040] The inner diameter side end wall 50 of the insulating cap piece 30B1 protrudes from the inner end of the upper coil side wall portion 46 of the insulating cap piece 30B1 in the radial direction toward the insulating cap piece 30B2, and the inner diameter side end wall 50 of the insulating cap piece 30B2 protrudes from the inner end of the upper coil side wall portion 46 of the insulating cap piece 30B2 in the radial direction toward the insulating cap piece 30B1. In the illustrated exemplary embodiment, a step portion 51 is formed on the inner surface of the inner diameter side end wall 50 of the insulating cap piece 30B1, and the tip of the inner diameter side end wall 50 of the insulating cap piece 30B2 is located radially inward of the tip of the inner diameter side end wall 50 of the insulating cap piece 30B1 and faces the step portion 51.

[0041] The outer diameter side end wall 52 of the insulating cap piece 30B1 protrudes from the outer end of the bottom coil side wall 44 of the insulating cap piece 30B1 toward the insulating cap piece 30B2 in the radial direction, and the outer diameter side end wall 52 of the insulating cap piece 30B2 protrudes from the outer end of the bottom coil side wall 44 of the insulating cap piece 30B2 in the radial direction toward the insulating cap piece 30B1. In the illustrated exemplary embodiment, a step 53 is formed on the inner surface of the outer diameter side end wall 52 of the insulating cap piece 30B2, and the tip of the outer diameter side end wall 52 of the insulating cap piece 30B1 is located radially inward of the tip of the outer diameter side end wall 52 of the insulating cap piece 30B2 and faces the step 53.

[0042] Fig. 5 is a cross-sectional view illustrating the details of the configuration shown in Fig. 4. In the exemplary embodiment shown in Fig. 5, in a cross section perpendicular to the axial direction, the length A1 of the upper coil-side connection piece portion 38 of the connection piece 32 is longer than the length A2 of the bottom coil-side connection piece portion 36 of the connection piece 32, and the length B1 of the upper coil-side wall portion 46 of the insulating cap piece 30B1 is equal to the length B2 of the bottom coil-side wall portion 44 of the insulating cap piece 30B1. Therefore, the radial distance d2 between the upper coil-side connection piece portion 38 of the connection piece 32 and the insulating cap piece 30B1 is shorter than the radial distance d3 between the bottom coil-side connection piece portion 36 of the connection piece 32 and the insulating cap piece 30B1.

[0043] Figure 6 is a view of the insulating cap 30B viewed axially from the axially opposite side of the stator core 2. As shown in Figure 6, each of the pair of insulating cap pieces 30B1, 30B2 includes an axial end wall 54. The axial end wall 54 of the insulating cap piece 30B1 protrudes toward the insulating cap piece 30B2 from an end of the main wall 43 of the insulating cap piece 30B1 opposite the stator core 2 (see Figure 2). The axial end wall 54 of the insulating cap piece 30B2 protrudes toward the insulating cap piece 30B1 from an end of the main wall 43 of the insulating cap piece 30B2 opposite the stator core 2.

[0044] 6 , an edge 55 of the axial end wall 54 of the insulating cap piece 30B1 opposite the main wall 43 has a groove 56 formed at a corner where the axial end wall 54 of the insulating cap piece 30B1 connects to the inner diameter side end wall 50. Furthermore, an edge 55 of the axial end wall 54 of the insulating cap piece 30B2 opposite the main wall 43 has a groove 56 formed at a corner where the axial end wall 54 of the insulating cap piece 30B2 connects to the outer diameter side end wall 52, and the tip of the outer diameter side end wall 52 of the insulating cap piece 30B1 is inserted into the groove 56 of the insulating cap piece 30B2. This allows the insulating cap 30B1 to be configured by combining the insulating cap pieces 30B1 and 30B2 while preventing the outer diameter side end wall 52 of the insulating cap piece 30B1 from interfering with the axial end wall 54 of the insulating cap piece 30B2.

[0045] Next, the effects achieved by the insulating cap 30B described with reference to FIGS. 4 to 6 will be described.

[0046] Compared to manually wrapping insulating tape around the coil connection portion connecting the coil end 3a1 of the bottom coil 3a and the coil end 3b1 of the top coil 3b, the insulating cap 30B allows for appropriate insulation of the coil connection portion 26 without relying on the skill of the operator, thereby achieving stable insulation performance. Furthermore, compared to manually wrapping insulating tape, the use of the insulating cap 30B allows for the thickness of the material used for insulation to be made thinner and more uniform, thereby promoting heat dissipation from the coil connection portion 26, improving ventilation, and suppressing a rise in temperature inside the insulating cap 30B.

[0047] Furthermore, since the insulating cap pieces 30B1 and 30B2 can be molded using the same mold, the manufacturing costs of the mold used for molding can be reduced.

[0048] Furthermore, as shown in Figure 5, even if the length A1 of the upper coil side connection piece portion 38 is longer than the length A2 of the bottom coil side connection piece portion 36 in a cross section perpendicular to the axial direction, the length B1 of the upper coil side wall portion 46 of the insulating cap piece 30B1 is equal to the length B2 of the bottom coil side wall portion 44 of the insulating cap piece 30B1 and is longer than the above-mentioned length A1, so that the insulating cap pieces 30B1 and 30B2 can be molded using the same mold (while the insulating cap pieces 30B1 and 30B2 have the same shape and dimensions), and the connection piece 32 can be covered by the insulating cap 30B.

[0049] Next, a modified example of the insulating cap 30B will be described. Fig. 7 is a cross-sectional view perpendicular to the axial direction of the insulating cap 30B and the coil connection portion 26 according to another embodiment. In the configuration shown in Fig. 7, reference numerals that are the same as those in Fig. 4 indicate the same configuration as the respective configurations in Fig. 4 unless otherwise specified, and description thereof will be omitted.

[0050] In the insulating cap 30B shown in Figure 7, the insulating cap piece 30B1 and the insulating cap piece 30B2 have the same shape and dimensions because they are molded using the same mold, but the insulating cap piece 30B1 and the insulating cap piece 30B2 each differ from the configuration shown in Figure 4 in that the bottom coil side wall portion 44 is inclined relative to the upper coil side wall portion 46.

[0051] 7, the upper coil side wall portion 46 of the insulating cap piece 30B1 extends radially, and the bottom coil side wall portion 44 of the insulating cap piece 30B1 is inclined relative to the radial direction so that the distance d4 between the bottom coil side wall portion 44 of the insulating cap piece 30B2 and the insulating cap piece 30B1 decreases radially outward. Also, the bottom coil side wall portion 44 of the insulating cap piece 30B2 extends radially, and the upper coil side wall portion 46 of the insulating cap piece 30B2 is inclined relative to the radial direction so that the distance d5 between the top coil side wall portion 46 of the insulating cap piece 30B1 and the insulating cap piece 30B1 decreases radially inward.

[0052] 7, the bottom coil side wall portion 44 of the insulating cap piece 30B1 extends on a straight line L1 inclined relative to the radial direction, the upper coil side wall portion 46 of the insulating cap piece 30B1 extends on a straight line L2 along the radial direction, the bottom coil side connection piece portion 36 of the connection piece 32 extends on a straight line La along the radial direction, and the upper coil side connection piece portion 38 of the connection piece 32 extends on a straight line Lb inclined relative to the radial direction. In the cross section shown in FIG. 7, if the angle between the lines La and Lb is θb and the angle between the lines L1 and L2 is θ1, the insulating cap 30B1 may be formed so as to satisfy θ1<θb / 2.

[0053] 2, the angle from position P1 of the first slot 19a to position P2 of the second slot 19b in the circumferential direction is θa. As shown in FIG. 7, the insulating cap 30B may be formed so that θ1<θa / 2 is satisfied. Here, position P1 of the first slot 19a in the circumferential direction is the center position of the first slot 19a in the circumferential direction (the center position of the first slot 19a in the groove width direction), and position P2 of the second slot 19b in the circumferential direction is the center position of the second slot 19b in the circumferential direction (the center position of the second slot 19b in the groove width direction). In some embodiments, θa may be equal to θb.

[0054] 7, the bottom coil side wall 44 of the insulating cap piece 30B1 is inclined radially so that the distance d4 between the bottom coil side wall 44 of the insulating cap piece 30B2 and the bottom coil side wall 44 decreases radially outward, and the top coil side wall 46 of the insulating cap piece 30B3 is inclined radially so that the distance d5 between the top coil side wall 46 of the insulating cap piece 30B1 and the bottom coil side wall 44 of the insulating cap piece 30B2 decreases radially inward. Therefore, compared to the configuration shown in FIG. 4, the insulating cap 30B can be made smaller in both the radial and circumferential directions.

[0055] Furthermore, by forming the insulating cap 30B so that θ1<θa / 2 is satisfied, the insulating cap 30B can be effectively downsized in both the radial and circumferential directions compared to the configuration shown in Fig. 4, etc. Furthermore, by forming the insulating cap 30B so that θ1<θb / 2 is satisfied, the insulating cap 30B can be effectively downsized in both the radial and circumferential directions compared to the configuration shown in Fig. 4, etc.

[0056] Fig. 8 is a cross-sectional view illustrating the details of the configuration shown in Fig. 7. In the exemplary embodiment shown in Fig. 8, in a cross section perpendicular to the axial direction, the length A1 of the upper coil-side connection piece portion 38 of the connection piece 32 is longer than the length A2 of the bottom coil-side connection piece portion 36 of the connection piece 32, and the length B1 of the upper coil-side wall portion 46 of the insulating cap piece 30B1 is equal to the length B2 of the bottom coil-side wall portion 44 of the insulating cap piece 30B1. Therefore, the radial distance d2 between the upper coil-side connection piece portion 38 of the connection piece 32 and the insulating cap piece 30B1 is shorter than the radial distance d3 between the bottom coil-side connection piece portion 36 of the connection piece 32 and the insulating cap piece 30B1.

[0057] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0058] For example, as shown in Fig. 9, in a cross section perpendicular to the axial direction, the length A1 of the upper coil side connection piece portion 38 of the connection piece 32 may be shorter than the length A2 of the bottom coil side connection piece portion 36 of the connection piece 32. Even in this case, in a cross section perpendicular to the axial direction, the length B1 of the upper coil side wall portion 46 of the insulating cap piece 30B1 is equal to and longer than the length B2 of the bottom coil side wall portion 44 of the insulating cap piece 30B1. Furthermore, in the cross section shown in Fig. 9, the distance d2 in the radial direction between the upper coil side connection piece portion 38 of the connection piece 32 and the insulating cap piece 30B1 is greater than the distance d3 in the radial direction between the bottom coil side connection piece portion 36 of the connection piece 32 and the insulating cap piece 30B1.

[0059] Thus, even if the length A1 of the upper coil side connection piece portion 38 is shorter than the length A2 of the bottom coil side connection piece portion 36 in a cross section perpendicular to the axial direction, the length B1 of the upper coil side wall portion 46 of the insulating cap piece 30B1 is equal to the length B2 of the bottom coil side wall portion 44 of the insulating cap piece 30B1 and is longer than the above length A2, so the insulating cap pieces 30B1 and 30B2 can be molded using the same mold (while the insulating cap pieces 30B1 and 30B2 have the same shape and dimensions), and the connection piece 32 can be covered by the insulating cap 30B.

[0060] Furthermore, the rotating electric machine of the present disclosure is not limited to a hydrogen-cooled rotating electric machine, but can be applied to all rotating electric machines (generators and motors) that have a jumper wire connection structure.

[0061] The contents described in each of the above embodiments can be understood, for example, as follows.

[0062] [1] An insulating cap for a stator coil according to at least one embodiment of the present disclosure (e.g., the insulating cap 30B described above) is an insulating cap for a stator coil applied to a stator coil (e.g., the stator coil 3 described above) of a rotating electric machine (e.g., the rotating electric machine 100 described above), wherein a bottom coil (e.g., the bottom coil 3a described above) and an upper coil (e.g., the upper coil 3b described above) are fitted to each of a plurality of slots (e.g., the plurality of slots 19 described above) formed on an inner peripheral surface (e.g., the inner peripheral surface 20 described above) of a stator core (e.g., the stator core 2 described above) of the rotating electric machine, and the insulating cap includes a first insulating cap piece (e.g., the insulating cap piece 30B1 described above) and a second insulating cap piece (e.g., the insulating cap piece 30B2 described above) that are combined with each other, Each of the first insulating cap piece and the second insulating cap piece includes a bottom coil side wall portion (e.g., the above-mentioned bottom coil side wall portion 44), an upper coil side wall portion (e.g., the above-mentioned upper coil side wall portion 46) located radially inward of the bottom coil side wall portion and shifted from the bottom coil side wall portion in the circumferential direction of the rotating electric machine, and an inclined wall portion (e.g., the above-mentioned inclined wall portion 48) connecting the bottom coil side wall portion and the upper coil side wall portion, and a coil end portion of the bottom coil (e.g., the above-mentioned coil end portion 3a1) located in a first slot (e.g., the above-mentioned first slot 19a), which is one of the plurality of slots, is located between the bottom coil side wall portion of the first insulating cap piece and the bottom coil side wall portion of the second insulating cap piece, Between the upper coil side wall portion of the first insulating cap piece and the upper coil side wall portion of the second insulating cap piece, a coil end portion of the upper coil (e.g., the above-mentioned coil end portion 3b1) that is located in a second slot (e.g., the above-mentioned second slot 19b) among the plurality of slots that is adjacent to the first slot in the circumferential direction of the rotating electric machine is arranged.

[0063] The insulating cap for a stator coil described in [1] above allows for proper insulation of the coil connection portion (coil connection portion) without relying on the skill of the worker, compared to manually wrapping insulating tape around the portion connecting the coil end of the bottom coil and the coil end of the top coil. This allows for stable insulation performance. Furthermore, compared to manually wrapping insulating tape, the use of the insulating cap allows for thinner and more uniform thickness of the material used for insulation, which promotes heat dissipation from the coil connection portion, improves ventilation, and suppresses temperature increases inside the insulating cap.

[0064] [2] In some embodiments, in the insulating cap for a stator coil described in [1] above, the first insulating cap piece and the second insulating cap piece are formed to have the same shape.

[0065] According to the insulating cap for the stator coil described in [2] above, the first insulating cap piece and the second insulating cap piece can be molded using the same mold, thereby reducing the manufacturing costs of the mold used for molding.

[0066] [3] In some embodiments, in the insulating cap for a stator coil described in [1] or [2] above, the first insulating cap piece and the second insulating cap piece are arranged rotationally symmetrically in a cross section perpendicular to the axial direction of the rotating electric machine.

[0067] According to the insulating cap for the stator coil described in [3] above, the first insulating cap piece and the second insulating cap piece can be molded using the same mold, thereby reducing the manufacturing costs of the mold used for molding.

[0068] [4] In some embodiments, in the insulating cap for a stator coil described in any of [1] to [3] above, in a cross section perpendicular to the axial direction of the rotating electric machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line (e.g., the above-mentioned straight line L1), and the upper coil side wall portion of the first insulating cap piece extends on a second straight line (e.g., the above-mentioned straight line L2) parallel to the first straight line.

[0069] According to the insulating cap for the stator coil described in [4] above, compared to manually wrapping insulating tape around the coil connection portion connecting the coil end of the bottom coil and the coil end of the top coil, the insulation treatment of the coil connection portion can be performed appropriately without relying on the skill of the worker, and stable insulation performance can be obtained.

[0070] [5] In some embodiments, in the insulating cap for a stator coil described in [4] above, in a cross section perpendicular to the axial direction, the bottom coil side wall portion of the second insulating cap piece extends on a third straight line (e.g., the above-mentioned line L3) parallel to the first straight line, and the top coil side wall portion of the second insulating cap piece extends on a fourth straight line (e.g., the above-mentioned line L4) parallel to the third straight line.

[0071] According to the insulating cap for the stator coil described in [5] above, compared to manually wrapping insulating tape around the coil connection portion connecting the coil end of the bottom coil and the coil end of the top coil, the insulation treatment of the coil connection portion can be performed appropriately without relying on the skill of the worker, and stable insulation performance can be obtained.

[0072] [6] In some embodiments, in the insulating cap for a stator coil described in any of [1] to [3] above, the bottom coil side wall portion of the first insulating cap piece is inclined relative to the radial direction so that the distance between it and the bottom coil side wall portion of the second insulating cap piece (e.g., the above-mentioned distance d4) decreases as it moves radially outward, and the upper coil side wall portion of the second insulating cap piece is inclined relative to the radial direction so that the distance between it and the upper coil side wall portion of the first insulating cap piece (e.g., the above-mentioned distance d5) decreases as it moves radially inward.

[0073] According to the insulating cap for a stator coil described in [6] above, the insulating cap can be made smaller in both the radial direction and the circumferential direction of the rotating electric machine.

[0074] [7] In some embodiments, in the insulating cap for a stator coil described in [6] above, in a cross section perpendicular to the axial direction of the rotating electric machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line (e.g., the above-mentioned straight line L1), and the top coil side wall portion of the first insulating cap piece extends on a second straight line (e.g., the above-mentioned straight line L2) inclined with respect to the first straight line, and when the angle from the position of the first slot (e.g., the above-mentioned position P1) to the position of the second slot (e.g., the above-mentioned position P2) in the circumferential direction is θa, and the angle between the first straight line and the second straight line is θ1, the following relationship is satisfied: θ1<θa / 2.

[0075] According to the insulating cap for a stator coil described in [7] above, the dimensions of the insulating cap can be reduced in both the radial and circumferential directions of the rotating electrical machine.

[0076] [8] A stator for a rotating electric machine according to at least one embodiment of the present disclosure includes a stator core (e.g., the stator core 2 described above), a stator coil (e.g., the stator coil 3 described above), and an insulating cap for a stator coil according to any one of [1] to [7] above.

[0077] According to the stator for a rotating electric machine described in [7] above, since it is equipped with the insulating cap for a stator coil described in any one of [1] to [7] above, it is possible to properly insulate the coil connection portion without depending on the skill of the worker, and stable insulating performance can be obtained. Furthermore, since the thickness of the material used for insulation can be made thin and uniform, it is possible to promote heat dissipation from the coil connection portion, improve ventilation performance, and suppress the rise in temperature inside the insulating cap.

[0078] [9] In some embodiments, the stator for a rotating electric machine described in [8] above includes connection pieces (e.g., the above-mentioned connection pieces 32, 34) that electrically connect the coil end of the bottom coil arranged in the first slot and the coil end of the upper coil arranged in the second slot, and the connection pieces include a bottom coil side connection piece portion (e.g., the above-mentioned bottom coil side connection piece 36) that contacts the coil end of the bottom coil arranged in the first slot, an upper coil side connection piece portion (e.g., the above-mentioned upper coil side connection piece 38) that is located radially inward of the bottom coil side connection piece portion and offset from the bottom coil side wall portion in the circumferential direction, and that contacts the coil end of the upper coil arranged in the second slot, and an inclined connection piece portion (e.g., the above-mentioned inclined connection piece 40) that connects the bottom coil side connection piece portion and the upper coil side connection piece portion.

[0079] According to the stator for a rotating electric machine described in [9] above, compared to when insulating tape is manually wrapped around the connecting pieces, the coil connection parts can be properly insulated without depending on the skill of the worker, and stable insulating performance can be obtained. Furthermore, compared to when insulating tape is manually wrapped around the connecting pieces, the use of the insulating cap allows the thickness of the material used for insulation to be thin and uniform, which promotes heat dissipation from the coil connection parts, improves ventilation performance, and suppresses temperature increases inside the insulating cap.

[0080]

[10] In some embodiments, in the stator for a rotating electric machine described in [9] above, the bottom coil side wall portion of the first insulating cap piece is inclined relative to the radial direction so that the distance between it and the bottom coil side wall portion of the second insulating cap piece (e.g., the above-mentioned distance d4) decreases as it moves radially outward, and the upper coil side wall portion of the second insulating cap piece is inclined relative to the radial direction so that the distance between it and the upper coil side wall portion of the first insulating cap piece (e.g., the above-mentioned distance d5) decreases as it moves radially inward.

[0081] According to the stator for a rotating electric machine described in the above

[10] , the insulating cap can be made smaller in both the radial direction and the circumferential direction of the rotating electric machine.

[0082]

[11] In some embodiments, in the stator for a rotating electric machine described in [9] or

[10] above, in a cross section perpendicular to the axial direction of the rotating electric machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line (e.g., the above-mentioned straight line L1), the upper coil side wall portion of the first insulating cap piece extends on a second straight line (e.g., the above-mentioned straight line L2) inclined with respect to the first straight line, the bottom coil side connection piece portion extends on a third straight line (e.g., the above-mentioned straight line La), and the upper coil side connection piece portion extends on a fourth straight line (e.g., the above-mentioned straight line Lb) inclined with respect to the third straight line, and when the angle between the first straight line and the second straight line is θ1 and the angle between the third straight line and the fourth straight line is θb, θ1 < θb / 2 is satisfied.

[0083] According to the stator for a rotating electric machine described in the above

[11] , the dimensions of the insulating cap can be reduced in both the radial direction and the circumferential direction of the rotating electric machine.

[0084]

[12] In some embodiments, in the stator for a rotating electric machine described in any of [9] to

[11] above, in a cross section perpendicular to the axial direction of the rotating electric machine, the upper coil side connection piece portion is longer than the bottom coil side connection piece portion, and the length of the upper coil side wall portion of the first insulating cap piece (e.g., the above-mentioned length B1) is equal to the length of the bottom coil side wall portion of the first insulating cap piece (e.g., the above-mentioned length B2) and is longer than the length of the upper coil side connection piece portion (e.g., the above-mentioned length A1).

[0085] According to the stator for a rotating electric machine described in

[12] above, even if the upper coil side connection piece portion is longer than the bottom coil side connection piece portion, the first insulating cap piece and the second insulating cap piece can be molded using the same mold (while the first insulating cap piece and the second insulating cap piece have the same shape and dimensions), and the connection piece can be covered with an insulating cap.

[0086]

[13] In some embodiments, in the stator for a rotating electric machine described in any of [9] to

[11] above, in a cross section perpendicular to the axial direction of the rotating electric machine, the upper coil side connection piece portion is shorter than the bottom coil side connection piece portion, and the length of the upper coil side wall portion of the first insulating cap piece (e.g., the above-mentioned length B1) is equal to the length of the bottom coil side wall portion of the first insulating cap piece (e.g., the above-mentioned length B2) and is longer than the length of the bottom coil side connection piece portion (e.g., the above-mentioned length A2).

[0087] According to the stator for a rotating electric machine described in

[13] above, even if the upper coil side connection piece portion is shorter than the bottom coil side connection piece portion, the first insulating cap piece and the second insulating cap piece can be molded using the same mold (while the first insulating cap piece and the second insulating cap piece have the same shape and dimensions), and the connection piece can be covered with an insulating cap.

[0088] REFERENCE SIGNS LIST 1 rotor 2 stator core 3 stator coil 3a bottom coil 3a1 coil end 3b top coil 3b1 coil end 4 stator 5 high voltage bushing 6 rotating electrical machine outer casing 7 terminal box 8 hydrogen cooler 9 end bracket 10 rocker device 11 leg 12 current transformer 13 crossover wire 14 lead wire 15, 42 filler 19 slot 19a first slot 19b second slot 20 inner circumferential surface 24 wedge 25, 26 coil connection portion 30, 30A, 30B insulating cap 30B1, 30B2 insulating cap piece 31 spacer 32, 34 connection piece 36 bottom coil side connection piece portion 38 top coil side connection piece portion 40 inclined connection piece portion 40a inclined connection plate portion 40b, 40c Curved plate portion 43 Main wall 44 Bottom coil side wall portion 46 Upper coil side wall portion 48 Inclined wall portion 48a Inclined plate portion 48b, 48c Curved wall portion 50 Inner diameter side end wall 51, 53 Step portion 52 Outer diameter side end wall 54 Axial direction end wall 55 Edge 56 Groove 100 Rotating electric machine

Claims

1. An insulating cap for a stator coil applied to a stator coil of a rotating electrical machine, wherein each of a plurality of slots formed on an inner peripheral surface of a stator core of the rotating electrical machine is equipped with a bottom coil and an upper coil disposed radially inward of the bottom coil with respect to the rotating electrical machine, the insulating cap includes a first insulating cap piece and a second insulating cap piece that are combined with each other, each of the first insulating cap piece and the second insulating cap piece includes a bottom coil side wall portion, an upper coil side wall portion located at a position shifted from the bottom coil side wall portion in a circumferential direction of the rotating electrical machine radially inward of the bottom coil side wall portion, and an inclined wall portion connecting the bottom coil side wall portion and the upper coil side wall portion, a coil end portion of the bottom coil disposed in a first slot which is one of the plurality of slots is disposed between the bottom coil side wall portion of the first insulating cap piece and the bottom coil side wall portion of the second insulating cap piece, and a coil end portion of the upper coil disposed in a second slot adjacent to the first slot in the circumferential direction of the rotating electrical machine among the plurality of slots is disposed between the upper coil side wall portion of the first insulating cap piece and the upper coil side wall portion of the second insulating cap piece.

2. The insulating cap for a stator coil according to claim 1, wherein the first insulating cap piece and the second insulating cap piece are formed in the same shape.

3. The insulating cap for a stator coil according to claim 2, wherein the first insulating cap piece and the second insulating cap piece are arranged rotationally symmetrically in a cross section orthogonal to an axial direction of the rotating electrical machine.

4. The insulating cap for a stator coil according to claim 1, wherein in a cross section orthogonal to the axial direction of the rotating electrical machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line, and the upper coil side wall portion of the first insulating cap piece extends on a second straight line parallel to the first straight line.

5. The insulating cap for a stator coil according to claim 4, wherein in the cross section orthogonal to the axial direction, the bottom coil side wall portion of the second insulating cap piece extends on a third straight line parallel to the first straight line, and the upper coil side wall portion of the second insulating cap piece extends on a fourth straight line parallel to the third straight line.

6. The bottom coil side wall portion of the first insulating cap piece is inclined with respect to the radial direction such that the distance from the bottom coil side wall portion of the second insulating cap piece decreases as it goes outward in the radial direction. The upper coil side wall portion of the second insulating cap piece is inclined with respect to the radial direction such that the distance from the upper coil side wall portion of the first insulating cap piece decreases as it goes inward in the radial direction. The insulating cap for a stator coil according to claim 1.

7. In a cross-section orthogonal to the axial direction of the rotating electrical machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line, and the upper coil side wall portion of the first insulating cap piece extends on a second straight line inclined with respect to the first straight line. Let the angle from the position of the first slot in the circumferential direction to the position of the second slot be θa, and the angle formed by the first straight line and the second straight line be θ1. Then, the insulating cap for a stator coil according to claim 6, which satisfies θ1 < θa / 2.

8. A stator for a rotating electrical machine, comprising: a stator core; a stator coil; and the insulating cap for a stator coil according to claim 1.

9. A connection piece for electrically connecting the coil end portion of the bottom coil disposed in the first slot and the coil end portion of the upper coil disposed in the second slot is provided. The connection piece includes a bottom coil side connection piece portion that contacts the coil end portion of the bottom coil disposed in the first slot, an upper coil side connection piece portion that is located at a position shifted from the bottom coil side wall portion in the circumferential direction and inside the radial direction with respect to the bottom coil side connection piece portion and contacts the coil end portion of the upper coil disposed in the second slot, and an inclined connection piece portion that connects the bottom coil side connection piece portion and the upper coil side connection piece portion. The stator for a rotating electrical machine according to claim 8.

10. The bottom coil side wall portion of the first insulating cap piece is inclined with respect to the radial direction such that the distance from the bottom coil side wall portion of the second insulating cap piece decreases as it goes outward in the radial direction. The upper coil side wall portion of the second insulating cap piece is inclined with respect to the radial direction such that the distance from the upper coil side wall portion of the first insulating cap piece decreases as it goes inward in the radial direction. The stator for a rotating electrical machine according to claim 9.

11. In a cross-section orthogonal to the axial direction of the rotating electrical machine, the bottom coil side wall portion of the first insulating cap piece extends on a first straight line, the upper coil side wall portion of the first insulating cap piece extends on a second straight line inclined with respect to the first straight line, the bottom coil side connection piece portion extends on a third straight line, and the upper coil side connection piece portion extends on a fourth straight line inclined with respect to the third straight line. When the angle formed by the first straight line and the second straight line is θ1 and the angle formed by the third straight line and the fourth straight line is θb, the stator for a rotating electrical machine according to claim 10, which satisfies θ1 < θb / 2.

12. In a cross-section orthogonal to the axial direction of the rotating electrical machine, the upper coil side connection piece portion is longer than the bottom coil side connection piece portion, the length of the upper coil side wall portion of the first insulating cap piece is equal to the length of the bottom coil side wall portion of the first insulating cap piece, and is longer than the upper coil side connection piece portion. The stator for a rotating electrical machine according to claim 9.

13. In a cross-section orthogonal to the axial direction of the rotating electrical machine, the upper coil side connection piece portion is shorter than the bottom coil side connection piece portion, the length of the upper coil side wall portion of the first insulating cap piece is equal to the length of the bottom coil side wall portion of the first insulating cap piece, and is longer than the bottom coil side connection piece portion. The stator for a rotating electrical machine according to claim 9.