Stator for rotating electrical machine

Abstract

To cool a stator for a rotary electric machine uniformly in a circumferential direction.SOLUTION: A stator for a rotary electric machine comprises: a stator core 20 provided with a plurality of slots 22 in a circumferential direction about an axis CL0 extending in a substantially horizontal direction; and coils arranged on the slots 22. The stator core 20 includes: a substantially annular-shaped ring flow channel PA1 to which cooling oil is guided via an inlet and which is formed around an axis CL1; and a plurality of axial flow channels PA2 in the circumferential direction that communicates with the ring flow channel PA1 and extends in the axial direction. The ring flow channel PA1 is formed such that the flow channel has a smaller cross-sectional area as it is further away from the inlet.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a stator for a rotating electric machine. [Background technology]

[0002] Conventionally, a technique for forming a cooling oil flow path in a stator core has been proposed (see, for example, Patent Document 1). In Patent Document 1, an annular flow path is provided between the outer peripheral surface of the stator core and the inner peripheral surface of the motor case, and multiple radially extending flow paths are provided to connect this flow path with multiple coil housing spaces. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-167045 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in Patent Document 1, when an annular flow passage is provided around the outer circumferential surface of the stator core, the flow rate of the cooling oil tends to vary circumferentially, making it difficult to cool the stator core uniformly in the circumferential direction. [Means for solving the problem]

[0005] A stator for a rotating electric machine according to one aspect of the present invention includes a stator core having a plurality of slots formed circumferentially around an axis extending substantially horizontally, and coils arranged in the slots. The stator core has a substantially annular first flow passage centered on the axis, through which cooling oil is guided via an inlet, and a plurality of circumferential second flow passages communicating with the first flow passage and extending in the axial direction. At least one of the first flow passage and the plurality of second flow passages is formed so that the cross-sectional area of the flow passage decreases with increasing distance from the inlet. [Effects of the Invention]

[0006] According to the present invention, the stator can be cooled uniformly in the circumferential direction.

Brief Description of the Drawings

[0007] [Figure 1] Front view showing the main part configuration of a rotating electrical machine including a stator for a rotating electrical machine according to an embodiment of the present invention. [Figure 2] Cross-sectional view taken along line II-II of FIG. 1. [Figure 3] Figure showing an example of the outflow amount of cooling oil from a plurality of axial flow paths provided in the stator core. [Figure 4] Front view showing the main part configuration of a stator core constituting a stator for a rotating electrical machine according to an embodiment of the present invention. [Figure 5] Figure showing a modified example of FIG. 4. [Figure 6] Figure showing a modified example of FIG. 5. [Figure 7] Figure showing a further modified example of FIG. 4. [Figure 8] View VIII in the direction of the arrow in FIG. 7. [Figure 9] Figure summarizing the operational effects of a stator for a rotating electrical machine according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 is a cross-sectional view showing the main part configuration of a rotating electrical machine 100 including a stator for a rotating electrical machine according to an embodiment of the present invention. The rotating electrical machine 100 is mounted on a hybrid vehicle or an electric vehicle and can be used as an electric motor for driving the vehicle or as a generator. Note that the rotating electrical machine 100 can also be mounted on other than a vehicle and used for various applications.

[0009] FIG. 1 is a front view orthogonal to the axis CL0 showing the main part configuration of the rotating electrical machine 100. As shown in FIG. 1, the rotating electrical machine 100 includes a rotor 1 that rotates about an axis CL0 extending in the horizontal direction (for example, the left-right direction), and a stator 2 provided outside the rotor 1 so as to surround the outer peripheral surface 1a of the rotor 1. A case 3 is disposed around the stator 2. Hereinafter, the direction in which the axis CL0 extends is defined as the axial direction, the direction extending radially from the axis CL0 is defined as the radial direction, and the direction along the circumference of a circle centered on the axis CL0 is defined as the circumferential direction. In FIG. 1, a reference line L1 extending in the vertical direction through the axis CL0 is shown.

[0010] The rotating electrical machine 100 is configured as, for example, an embedded magnet type synchronous motor. Therefore, the rotor 1 has a substantially annular rotor core 10 centered on the axis CL0, and a plurality of circumferentially arranged magnetic pole portions (not shown) formed on the rotor core 10. Permanent magnets are embedded in the magnetic pole portions. An unillustrated rotor shaft, which constitutes the output shaft of the rotating electrical machine 100, is fitted to the inner peripheral surface 10a of the rotor core 10, and the rotor 1 rotates integrally with the rotor shaft. The outer peripheral surface 1a of the rotor 1 corresponds to the outer peripheral surface of the rotor core 10. The rotor core 10 is formed by axially laminating a plurality of (for example, several tens of) electromagnetic steel sheets made of a magnetic metal.

[0011] The stator 2 has a substantially annular stator core 20 centered on the axis CL0 having an inner peripheral surface 2a disposed at a predetermined interval in the radial direction from the outer peripheral surface 1a of the rotor 1, and a coil 21 attached to the stator core 20. The stator core 20 is configured by axially laminating a plurality of electromagnetic steel sheets made of a magnetic metal.

[0012] The stator core 20 has a plurality of circumferential teeth 23 that protrude radially inward from a substantially cylindrical yoke 25 at equal circumferential intervals. A plurality of circumferential slots 22 are provided between circumferentially adjacent teeth 23, extending radially outward from the inner circumferential surface 20a, and a coil 21 is disposed in each slot 22. Although the slots 22 are provided around the entire circumference of the inner circumferential surface 20a, for convenience, only slots 22 near the top (uppermost part) of the stator core 20 are shown in FIG. 1. The total number of slots 22 is, for example, 48. The total number of slots 22 may be more or less than 48. The outer circumferential surface 20b of the stator core 20 is fitted liquid-tightly into the inner circumferential surface 31 of the substantially cylindrical case 3.

[0013] The coils 21 are formed of conductor segments having a substantially rectangular cross section. The coils 21 may also be conductor segments having a circular cross section. The coils 21 are formed as a three-phase coil, including a U-phase coil, a V-phase coil, and a W-phase coil. When the rotating electric machine 100 is used as an electric motor, three-phase AC power is supplied to each coil 21 from a power conversion device (not shown). This generates a magnetic field in the stator 2, and this magnetic field interacts with a magnetic field generated by the permanent magnets in the magnetic pole portions of the rotor 1, causing the rotor 1 to rotate. As a result, a driving force is generated, and the vehicle travels. When the rotating electric machine 100 is used as a generator, the three-phase AC power generated by driving the rotating electric machine 100 is supplied to a power conversion device or the like.

[0014] 2 is a cross-sectional view of the top (uppermost part) of the rotating electric machine 100 of FIG. 1. That is, it is a cross-sectional view taken along line II-II on reference line L1. As shown in FIGS. 1 and 2, a circular or approximately circular recess 24 of a predetermined depth D is provided in the axial center of the outer peripheral surface 20b of the stator core 20. The width W (axial length) of the recess 24 is constant over the entire circumference of the stator core 20. The recess 24 can be formed in the axial center of the stator core 20 by stacking electromagnetic steel sheets having a smaller outer diameter than the electromagnetic steel sheets on the outside of the axial center.

[0015] A plurality of circular through-holes 26 are formed in the yoke 25 of the stator core 20, axially penetrating the stator core 20, at equal intervals around the entire circumference of the stator core 20 along a reference circle C1 centered on the axis CL0. For convenience, only the through-holes 26 near the top of the stator 20 are shown in FIG.

[0016] The through holes 26 are provided, for example, radially outward from the slots 22, at intervals twice the interval (angular interval) at which the slots 22 are arranged. Therefore, the number of through holes 26 is half the number of slots 22. The number of through holes 26 may be the same as or greater than the number of slots 22. The slots 22 and the through holes 26 may not be provided in the same phase about the axis CL0, but may be provided in different phases from each other. For example, the through holes 26 may be located radially outward from the slots 22 and between slots adjacent in the circumferential direction. The diameter of the through holes 26 is smaller than the depth D of the recesses 24, and the through holes 26 intersect with the recesses 24 at the axial center of the stator core 20.

[0017] An insulating member 40 having a substantially rectangular frame-like cross section is placed in the slot 22. The insulating member 40 is made of, for example, foldable insulating paper. The axial length of the insulating member 40 is the same as the axial length of the slot 22. A substantially rectangular parallelepiped storage space is formed inside the insulating member 40, and four conductor segments 210 forming the coil 21 are arranged in a row in the radial direction in the storage space. The number of conductor segments 210 in the slot may be more or less than four. The periphery of each conductor segment 210 is covered with an insulating coating.

[0018] In the stator 2 configured as described above, an annular flow passage centered on the axis CL0, i.e., annular flow passage PA1, is formed between the recess 24 of the stator core 20 and the inner circumferential surface 31 of the case 3. Furthermore, the stator core 20 defines a plurality of flow passages, i.e., a plurality of axial flow passages PA2, communicating with the annular flow passage PA1 by a plurality of through-holes 26. The depth D of the recess 24 corresponds to the radial width (radial length) of the annular flow passage PA1. Note that the annular flow passage PA1 includes not only a curve (annular flow passage curve, described later) extending circumferentially through the midpoint of the depth D that is a circle with a constant curvature centered on the axis CL0, but also a curve with a curvature that varies circumferentially. In other words, the annular flow passage PA1 need only be provided around the entire circumference centered on the axis CL0, and the flow passage shape does not need to be a perfect circle.

[0019] A flange portion 32 is provided at the top of the outer peripheral surface of the case 3. A through hole 32a is formed in the flange portion 32, penetrating the case 3 in the radial direction, and the external space of the case 3 communicates with the annular flow path PA1 via the through hole 32a. The through hole 32a forms a supply flow path PA0 for the cooling medium.

[0020] The top of the stator core 20, which communicates with the through-hole 32a, is an inlet portion 27, and a cooling medium is supplied to the annular flow path PA1 from the outside of the case 3 through the inlet portion 27. The cooling medium is, for example, cooling oil. The supplied cooling oil flows circumferentially along the annular flow path PA1. The cooling oil then flows from the annular flow path PA1 into the axial flow path PA2 and flows axially along the axial flow path PA2. This flow of cooling oil cools the stator core 20, and as the stator core 20 around the slots 22 is cooled, the coils 21 are cooled. The cooling oil that has flowed through the axial flow path PA2 flows out from both axial end faces of the stator core 20. This allows the cooling oil to be applied to the coil ends, facilitating cooling of the coils 21.

[0021] Incidentally, the annular flow path PA1 has a substantially rectangular cross-sectional shape with an axial width W and a radial depth D. However, if the cross-sectional area of the annular flow path PA1 is formed to be constant over the entire circumference, there will be a difference in the circumferential direction in the outflow rate of the cooling oil from the axial flow path PA2. FIG. 3 is a diagram showing an example of the outflow rate of the cooling oil from each axial flow path PA2. As shown in FIG. 3, the outflow rate of the cooling oil particularly increases in the vicinity of the top of the stator core 20. This is because the cooling oil is supplied to the annular flow path PA1 from the top (0°, 360°), and the closer to the top, the higher the pressure of the cooling oil in the annular flow path PA1. From the middle part (90°, 270°) in the height direction of the stator core 20 to the bottom part (180°), the outflow rate of the cooling oil also decreases. However, the degree of decrease in the outflow rate from the middle part in the height direction to the bottom part is smaller than the degree of decrease in the outflow rate from the top to the middle part in the height direction. In addition, due to the action of the gravity of the cooling oil, the outflow rate in the middle part in the height direction may be less than the outflow rate at the bottom part, and the outflow rate may be minimized in the middle part in the height direction.

[0022] When there is a difference in the circumferential direction in the flow rate of the cooling oil flowing through the axial flow path PA2 in this way, it is difficult to cool the stator core 20 uniformly in the circumferential direction by the flow of the cooling oil. Therefore, in order to cool the stator core 20 uniformly in the circumferential direction, the stator 2 for a rotating electrical machine in this embodiment is configured as follows.

[0023] FIG. 4 is a front view showing the main part configuration of a single stator core constituting the stator 2 for a rotating electrical machine according to this embodiment, showing the configuration from the top (0°) to the middle part (90°) in the height direction, that is, the configuration of about 1 / 4 of the whole circle. The stator core 20 is configured symmetrically with respect to the reference line L1. The stator core 20 in FIG. 4 is characterized by the configuration of the recess 24.

[0024] As shown in FIG. 4, the outer peripheral surface 20b of the stator core 20 is a cylindrical surface centered on the axis CL0, and the distance from the axis CL0 to the outer peripheral surface 20b (outer radius R1) is constant over the entire circumference. On the other hand, the bottom surface 24a of the recess 24 is a curved surface but not a cylindrical surface in the strict sense, and the distance from the axis CL0 to the bottom surface 24a (inner radius R2) gradually increases from the top to the middle part in the height direction.

[0025] Therefore, the depth D of the annular flow passage PA1, which is the outer radius R1 minus the inner radius R2, i.e., the radial width (radial length), gradually decreases from the top of the stator core 20 to the middle in the height direction. On the other hand, the width W (axial length) of the annular flow passage PA1 is constant over the entire circumference. As a result, the cross-sectional area of the annular flow passage PA1 gradually decreases from the top of the stator core 20 to the middle in the height direction.

[0026] As shown in FIG. 3, the degree of decrease in the amount of cooling oil outflow is small from the middle to the bottom of the stator core 20 in the height direction. In consideration of this, although not shown in the figure, below the middle of the stator core 20 in the height direction, the bottom surface 24a of the recess 24 is a cylindrical surface centered on the axis CL0. Therefore, from the middle to the bottom of the stator core 20 in the height direction, the inner radius R2 is constant, and therefore the cross-sectional area of the annular flow path PA1 is also constant. Note that, similar to the case from the top to the middle of the height direction, the inner radius R2 may be gradually decreased from the middle to the bottom.

[0027] In this way, the cross-sectional area of the annular flow path PA1 gradually decreases from the top to the intermediate portion in the height direction of the stator core 20, thereby suppressing a decrease in the pressure of the cooling oil downstream of the supply flow path PA0. This increases the amount of cooling oil flowing through the axial flow path PA2 at the intermediate portion in the height direction of the stator core 20 and below it, allowing the cooling oil to flow uniformly around the entire circumference of the stator core 20.

[0028] FIG. 4 shows a curve C2 passing through the midpoint of the depth D of the recess 24, i.e., a curve corresponding to the radius of the annular flow passage PA1 centered on the axis CL0. For convenience, this curve C2 is referred to as the annular flow passage curve, which indicates the shape of the annular flow passage PA1. The annular flow passage curve C2 is not a circle centered on the axis CL0, but gradually shifts radially outward from the top of the stator core 20 to the intermediate portion in the height direction. Note that the annular flow passage curve C2 may be a circle centered on the axis CL0, and the cross-sectional area of the annular flow passage PA1 may be gradually reduced. That is, the outer radius R1 may be gradually reduced and the inner radius R2 may be gradually increased from the top to the intermediate portion in the height direction.

[0029] Fig. 5 is a diagram showing a modified example of Fig. 4. In Fig. 5, the configuration of the through hole 26 is different from that in Fig. 4. Note that, unlike Fig. 4, the bottom surface 24a of the recess 24 is a cylindrical surface centered on the axis CL0. Therefore, the inner radius R2 is constant around the entire circumference of the stator core 20, and the cross-sectional area of the annular flow path PA1 is also constant.

[0030] As shown in Fig. 5, the multiple through holes 26 are arranged along a reference circle C1 centered on the axis CL0, and the diameters of the through holes 26 gradually decrease from the top to the middle in the height direction. For example, the diameter D2 of the through holes 26 at the middle in the height direction is approximately half the diameter D1 of the through holes 26 at the top. Although not shown in the figure, the diameter of the through holes 26 is constant (= D2) from the middle in the height direction of the stator core 20 to the lowest part. Note that the diameter of the through holes 26 may gradually decrease from the middle in the height direction to the lowest part.

[0031] This gradually reduces the cross-sectional area of the axial flow path PA2, thereby preventing a decrease in the pressure of the cooling oil downstream of the supply flow path PA0. As a result, the amount of cooling oil flowing through the axial flow path PA2 increases at the intermediate portion of the stator core 20 in the height direction and below the intermediate portion, and the cooling oil flows uniformly around the entire circumference of the stator core 20.

[0032] FIG. 6 is a diagram showing a modified example of FIG. 5. In FIG. 5, a plurality of through holes 26 are arranged along a reference circle C1 centered on the axis CL0, but in FIG. 6, a plurality of through holes 26 are arranged along a curve C3. This curve C3 gradually shifts radially outward from the top of the stator core 20 to the middle part in the height direction, similar to the annular flow path curve C2 in FIG. 4. Therefore, the distance (pitch diameter) from the axis CL0 to the curve C3 is not constant, and the distance from the axis CL0 to the top through hole 26 is short less than

[0033] In the above, the annular flow path PA1 is formed by the recess 24 provided on the outer peripheral surface 20b of the stator core 20, but the annular flow path PA1 may be formed by through holes provided inside the stator core 20. FIG. 7 is a front view of the stator core 20 showing an example thereof, and FIG. 8 is a view taken in the direction of arrow VIII in FIG. 7 (viewed from above). A plurality of through holes 26 are provided in the yoke 25 of the stator core 20 in the circumferential direction, and an axial flow path PA2 communicating with the annular flow path PA1 is formed by the through holes 26 (see FIG. 1). However, in FIGS. 7 and 8, for the sake of simplicity, the illustration of the through holes 26 is omitted. The stator core 20 is symmetrically configured with respect to a reference line L1 extending in the vertical direction.

[0034] As shown in FIGS. 7 and 8, a plurality of arc-shaped slit holes 28 centered on the axis CL0 are formed in the stator core 20. More specifically, when a plurality of slit holes 28 from the top to the bottom of the stator core 20 are represented by slit holes 281 to 285, as shown in FIG. 8, the circumferentially adjacent slit holes 28 are provided with their positions shifted from each other in the axial direction. That is, the slit holes 281, 283, and 285 are provided in the first axial region AR1 (electromagnetic steel sheet of the first region AR1), and the slit holes 282 and 284 are provided in the second axial region AR2 (electromagnetic steel sheet of the second region AR2) adjacent to the first region AR1. Note that no slit holes 28 are provided in the electromagnetic steel sheets outside the first region AR1 and the second region AR2, thereby forming a slit-shaped space (divided flow path) inside the stator core 20.

[0035] 7, the slit holes 281-285 are provided so as to be shifted radially outward from the axis CL0 as they extend downward from the top. Therefore, the distance between the outer peripheral surfaces of the slit holes 281-285 and the outer peripheral surface of the stator core 20 is approximately constant over the entire circumference of the stator core 20, whereas the distance between the outer peripheral ends of the slots 22 and the inner peripheral surfaces of the slit holes 281-285 increases downward.

[0036] The slit holes 281-285 extend in the circumferential direction such that both circumferential ends of the slit holes 281, 283, and 285 overlap both circumferential ends of the slit holes 282 and 284. The slit holes 281-285 communicate with each other around the entire circumference via overlapping portions 29 at both circumferential ends. This allows the multiple divided flow paths to communicate with each other, thereby forming an annular flow path PA1 centered on the axis CL0 as a whole. As shown in FIGS. 7 and 8 , a cooling oil supply hole 271 is opened to the slit hole 281 in one axial end face of the top of the stator core 20. The opening at the end of the supply hole 271 is an inlet portion 27, and cooling oil is supplied to the annular flow path PA1 from the outside of the stator core 20 via the inlet portion 27.

[0037] As shown in FIG. 8, the width W1 (axial length) of the slits 281, 283, and 285 is equal to the width W2 (axial length) of the slits 282 and 284. These widths W1 and W2 are half the width of the recess 24 in FIGS. 4 to 6. As shown in FIG. 7, the radial width S of the slits 281 to 285 determines the radial length of the annular flow path PA1 and corresponds to the depth D of the annular flow path PA1 in FIGS. 4 to 6. This width S is constant for each of the slits 281 to 285. However, when comparing the slits 281 to 285, the width S gradually decreases from the top to the bottom. Therefore, the cross-sectional area of the slit 281 at the top is maximum, and the cross-sectional area of the slit 285 at the bottom is minimum. This prevents a decrease in cooling oil pressure from the top to the bottom, allowing cooling oil to flow evenly through the multiple axial flow paths PA2 (FIG. 1) in the circumferential direction.

[0038] In order to prevent the cross-sectional area of the annular flow path PA1 from changing suddenly at the overlapping portion 29, the widths S of the slits 281-285 may be gradually reduced downward for each of the slits 281-285, rather than being constant for each of the slits 281-285. This causes the cross-sectional area of the annular flow path PA1 to continuously decrease downward.

[0039] 7, the cross-sectional area of the slit holes 28 gradually decreases from the top to the bottom of the stator core 20, but the cross-sectional area of the slit holes 28 may gradually decrease from the top to the middle in the height direction, and then the cross-sectional area may be constant from the middle in the height direction to the bottom. That is, the radial width S of the slit holes 281-283 may gradually decrease from the slit hole 281 to the slit hole 283, and the width S may be constant from the slit hole 283 to the slit hole 285.

[0040] FIG. 9 summarizes the effects of the above-described embodiment. In FIG. 9, the reference example is an example in which the recesses 24 form annular flow passages PA1 in a single axial row, as in FIG. 4, but the radial width (depth D of the recesses 24) and radius (radius of the annular flow passage curve C2) of the annular flow passage PA1 are different from those in FIG. 4. That is, in the reference example, the radial width of the annular flow passage PA1 is constant around the entire circumference of the stator core 20, and the radius of the annular flow passage curve C2 is constant around the entire circumference. In this example, the flow rate of the cooling oil gradually decreases downward. Furthermore, because the recesses 24 block the generation of a magnetic path in the stator core 20, the motor torque decreases by a predetermined amount (e.g., about 7%) compared to a case in which the recesses 24 are not provided. Note that the change in motor torque is a value obtained by analysis.

[0041] The first embodiment is an example in which the radial width of the annular flow path PA1 (the depth D of the recess 24) is gradually decreased downward, and the radius of the annular flow path curve C2 is made constant over the entire circumference of the stator core 20. In this example, since the cross-sectional area of the annular flow path PA1 gradually decreases downward, the flow rate of the cooling oil becomes substantially constant over the entire circumference. Further, since the range of the recess 24 is smaller than that in the reference example, the degree of decrease in the motor torque is also smaller than that in the reference example.

[0042] The second embodiment is an example in which, as shown in FIG. 4, the radial width of the annular flow path PA1 is gradually decreased downward, and the annular flow path curve C2 is gradually shifted radially outward downward. In this example, since the cross-sectional area of the annular flow path PA1 gradually decreases downward, the flow rate of the cooling oil becomes substantially constant over the entire circumference. Further, since the range of the recess 24 is shifted radially outward more than that in the first embodiment, torque reduction is suppressed, and the degree of decrease in the motor torque is smaller than that in the first embodiment.

[0043] The third embodiment is an example in which, as shown in FIG. 5, the diameters of the plurality of axial flow paths PA2 are gradually decreased downward, and the plurality of axial flow paths PA2 are arranged along a reference circle C1 centered on the axis CL0. Therefore, the pitch diameter of the plurality of axial flow paths PA2 centered on the axis CL0 is constant over the entire circumference. In this example, since the cross-sectional area of the axial flow path PA2 gradually decreases downward, the flow rate of the cooling oil becomes substantially constant over the entire circumference. Further, since the total area of the through holes 26 in the stator core 20 decreases, the degree of decrease in the motor torque is also small.

[0044] The fourth embodiment is an example in which, as shown in FIG. 6, the diameters of the plurality of axial flow paths PA2 are gradually decreased downward, and the plurality of axial flow paths PA2 are arranged by being gradually shifted radially outward downward. Therefore, the pitch diameter centered on the axis CL0 of the plurality of axial flow paths PA2 gradually increases downward. In this example, since the cross-sectional area of the axial flow path PA2 gradually decreases downward, the flow rate of the cooling oil becomes substantially constant over the entire circumference. Further, since the through holes 26 are arranged with a shift radially outward, torque reduction is suppressed, and the degree of reduction of the motor torque is smaller than that of the third embodiment.

[0045] The fifth embodiment is an example in which, as shown in FIG. 7, the annular flow path PA1 is formed in two axial rows by the slit holes 28, the radial width of the annular flow path PA1 is gradually decreased downward, and the annular flow path curve C2 is gradually shifted outward downward. In this example, since the cross-sectional area of the annular flow path PA1 gradually decreases downward, the flow rate of the cooling oil becomes substantially constant over the entire circumference. Further, since the range of the recess 24 is shifted radially outward, the degree of reduction of the motor torque is also small.

[0046] According to the present embodiment, the following operational effects can be achieved. (1) The stator 2 for a rotating electrical machine includes a stator core 20 provided with a plurality of slots 22 in the circumferential direction about an axis CL0 extending in a substantially horizontal direction, and coils 21 disposed in the slots 22 (FIG. 1). The stator core 20 has a substantially annular annular flow path PA1 centered on the axis CL0 through which cooling oil is introduced via an inlet portion 27, and a plurality of axial flow paths PA2 extending in the axial direction and communicating with the annular flow path PA1 (FIGS. 1 and 2). At least one of the annular flow path PA1 and the plurality of axial flow paths PA2 is formed such that the flow path cross-sectional area becomes smaller as it moves away from the inlet portion 27 (FIGS. 4 and 5). Thereby, the pressure of the cooling oil increases downward as compared with the case where the flow path cross-sectional area is constant in the circumferential direction. As a result, the cooling oil can flow through the stator core 20 uniformly in the circumferential direction, and the stator core 20 can be cooled uniformly in the circumferential direction.

[0047] (2) The annular flow passage PA1 is formed so that the flow passage cross-sectional area decreases with increasing distance from the inlet portion 27, and so that the distance from the axis CL0 to the annular flow passage PA1 increases with increasing distance from the inlet portion 27, i.e., so that the annular flow passage curve C2 is shifted downward and radially outward ( FIG. 4 ). This prevents the recess 24 from interfering with the magnetic path of the stator core 20, and suppresses a decrease in motor torque when the rotating electric machine 100 is used as a motor.

[0048] (3) The multiple axial flow passages PA2 are formed so that the flow passage cross-sectional area decreases with increasing distance from the inlet portion 27, and the distance from the axis CL0 to the multiple axial flow passages PA2 increases with increasing distance from the inlet portion 27 (FIG. 6). This allows the cooling oil flowing through the axial flow passages PA2 to increase downward. Therefore, even if the cross-sectional area of the annular flow passage PA1 is constant in the circumferential direction, the stator core 20 can be cooled uniformly in the circumferential direction. Furthermore, a decrease in motor torque can be suppressed.

[0049] (4) The annular flow path PA1 is formed so that the flow path cross-sectional area decreases with increasing distance from the inlet portion 27, and is composed of a plurality of substantially arc-shaped slits 281-285 (divided flow paths) including circumferentially adjacent slits 281, 283, 285 (first divided flow path) and slits 282, 284 (second divided flow path) ( FIG. 7 ). The slits 281, 283, 285 and the slits 282, 284 are provided with offset positions in the axial direction ( FIG. 8 ). This makes it possible to form the annular flow path PA1 inside the stator core 20, without using the inner circumferential surface 31 of the case 3 ( FIG. 1 ), such that a decrease in flow rate downward is suppressed.

[0050] (5) The inlet portion 27 is provided at the top of the annular flow passage PA1, which extends from the top to the middle and bottom of the stator core 20 (FIG. 1). The annular flow passage PA1 is formed so that the flow passage cross-sectional area gradually decreases from the top to the middle (FIG. 4). This allows the cooling oil to flow uniformly around the stator core 20 in the circumferential direction, even when the decrease in the outflow rate of the cooling oil from the top (top) to the middle of the stator core 20 is particularly large (FIG. 3).

[0051] This embodiment can be modified in various ways. Several modifications will be described below. In the above embodiment, the inlet portion 27 that introduces cooling oil into the annular flow path PA1 (first flow path) is provided at the top of the stator core 20, but the inlet portion may be provided at a location other than the top. In other words, as long as the annular flow path PA1 (first flow path) or the multiple axial flow paths PA2 (second flow paths) are formed so that the flow path cross-sectional area decreases with increasing distance from the inlet portion 27, the location of the inlet portion is not limited to that of the above embodiment. In the above embodiment, the multiple axial flow paths PA2 are formed by the multiple through holes 26 that penetrate the stator core 20 in the axial direction, but the second flow paths may be provided in the slots 22. Therefore, the through holes 26 may be omitted.

[0052] In the above embodiment, the flow paths are formed in the stator core 20 so that the cross-sectional area of the annular flow path PA1 or the cross-sectional areas of the multiple axial flow paths PA2 decrease with increasing distance from the inlet portion 27. However, the flow paths may be formed in the stator core 20 so that the cross-sectional area of the annular flow path PA1 and the cross-sectional areas of the multiple axial flow paths PA2 decrease with increasing distance from the inlet portion 27. That is, the flow paths may be formed by combining the first to fifth embodiments of FIG. 9. In the above embodiment, the cross-sectional area of the annular flow path PA1 is reduced by narrowing the radial width thereof. However, instead of or in addition to this, the cross-sectional area of the flow path may be reduced by narrowing the axial width of the annular flow path PA1.

[0053] In the above embodiment, cooling oil is supplied to the cooling flow path, but the cooling medium is not limited to cooling oil. In the above embodiment, the rotor 1 is arranged radially inside the stator 2, but the rotor can also be arranged radially outside the stator. In the above embodiment, the stator for the rotating electrical machine is applied to a vehicle, but the stator for the rotating electrical machine of the present invention can also be applied to other than vehicles.

[0054] The above description is merely an example, and the present invention is not limited to the above-described embodiments and modified examples as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiments and modified examples, and it is also possible to combine the modified examples with each other.

Explanation of Signs

[0055] 2 Stator, 20 Stator core, 21 Coil, 22 Slot, 24 Recess, 27 Inlet portion, 28 Slit hole, 281~285 Slit holes, PA1 Annular flow path, PA2 Axial flow path

Claims

1. A stator core provided with a plurality of slots in the circumferential direction about an axis extending in a substantially horizontal direction, and a coil disposed in the slots, a stator for a rotating electrical machine comprising: wherein the stator core has a substantially annular first flow path centered on the axis, into which cooling oil is introduced through an inlet portion, and a plurality of second flow paths extending in the axial direction and communicating with the first flow path, wherein at least one of the first flow path and the plurality of second flow paths is formed such that the cross-sectional area of the flow path decreases as it moves away from the inlet portion, a stator for a rotating electrical machine.

2. In the stator for a rotating electrical machine according to Claim 1, the first flow path is formed such that the cross-sectional area of the flow path decreases as it moves away from the inlet portion, and the distance from the axis to the first flow path increases as it moves away from the inlet portion, a stator for a rotating electrical machine.

3. In the stator for a rotating electrical machine according to Claim 1, the plurality of second flow paths are formed such that the cross-sectional area of the flow path decreases as it moves away from the inlet portion, and the distance from the axis to the plurality of second flow paths increases as it moves away from the inlet portion, a stator for a rotating electrical machine.

4. In the stator for a rotating electrical machine according to any one of Claims 1 to 3, the first flow path has a plurality of divided flow paths in a substantially arc shape including a first divided flow path and a second divided flow path adjacent to each other in the circumferential direction, wherein the first divided flow path and the second divided flow path are provided with a shift in position in the axial direction, a stator for a rotating electrical machine.

5. In the stator for a rotating electrical machine according to any one of Claims 1 to 3, the stator core has an upper portion, a lower portion, and an intermediate portion between the upper portion and the lower portion, the inlet portion is provided in the upper portion of the stator core, wherein the first flow path is formed such that the cross-sectional area of the flow path gradually decreases from the upper portion to the intermediate portion of the stator core and becomes constant from the intermediate portion to the lower portion, a stator for a rotating electrical machine.

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