Stator for rotary electric 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] JP 2011-167045 A 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 is likely to vary in the circumferential direction, making it difficult to uniformly cool the stator core 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 provided in the circumferential direction around an axis extending in a substantially horizontal direction, and a coil 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 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. Effect 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] 1 is a front view showing a configuration of a main part of a rotating electric machine including a stator for a rotating electric machine according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 4 is a diagram showing an example of the amount of cooling oil flowing out from a plurality of axial flow passages provided in a stator core. [Figure 4] 1 is a front view showing a configuration of a main part of a stator core that constitutes a stator for a rotating electric machine according to an embodiment of the present invention; [Diagram 5] FIG. 5 is a diagram showing a modification of FIG. 4. [Figure 6] FIG. 6 is a diagram showing a modification of FIG. 5 . [Figure 7] FIG. 5 is a diagram showing a further modified example of FIG. 4. [Figure 8] FIG. 8 is a view taken along line VIII of FIG. [Figure 9] 4 is a diagram summarizing the effects of the stator for a rotating electric machine according to the embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0010] The rotating electric machine 100 is configured as, for example, an embedded magnet type synchronous motor. Thus, the rotor 1 has a rotor core 10 having a substantially annular shape centered on an axis CL0, and a plurality of magnetic pole portions (not shown) formed in the rotor core 10 in the circumferential direction. Permanent magnets are embedded in the magnetic pole portions. For example, a rotor shaft (not shown) constituting the output shaft of the rotating electric machine 100 is fitted into an 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 stacking a plurality of (for example, several tens of) magnetic metal magnetic steel plates in the axial direction.

[0011] The stator 2 has a substantially annular stator core 20 centered on an axis CL0, with an inner circumferential surface 2a disposed at a predetermined distance in the radial direction from the outer circumferential surface 1a of the rotor 1, and a coil 21 attached to the stator core 20. The stator core 20 is formed by stacking multiple electromagnetic steel plates made of a magnetic metal in the axial direction.

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

[0013] The coil 21 is composed of a conductor segment having a substantially rectangular cross section. The coil 21 may be a conductor segment having a circular cross section. The coil 21 includes a U-phase coil, a V-phase coil, and a W-phase coil, and is configured as a three-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 the rotor 1 rotates due to the interaction between this magnetic field and the magnetic field generated by the permanent magnets of the magnetic poles of the rotor 1. As a result, a driving force is generated and the vehicle runs. 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 in FIG. 1. That is, it is a cross-sectional view taken along line II-II on the reference line L1. As shown in FIGS. 1 and 2, a circular or nearly circular recess 24 of a predetermined depth D is provided in the axial center of the outer circumferential 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, which penetrate the stator core 20 in the axial direction, 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 in the vicinity of the top of the stator 20 are shown in FIG.

[0016] The through holes 26 are provided, for example, radially outside the slots 22 at intervals (angular intervals) twice the intervals at which the slots 22 are arranged. Therefore, the number of the through holes 26 is 1 / 2 the number of the slots 22. The number of the through holes 26 may be the same as the number of the slots 22, or may be greater than the number of the 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. For example, the through holes 26 may be provided radially outside the slots 22 and between slots adjacent to each other 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 disposed in the slot 22. The insulating member 40 is formed, for example, from a 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 accommodation space is formed inside the insulating member 40, and four conductor segments 210 forming the coil 21 are disposed in a row in the radial direction in the accommodation 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 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 peripheral surface 31 of the case 3. Furthermore, in the stator core 20, a plurality of flow passages communicating with the annular flow passage PA1, i.e., a plurality of axial flow passages PA2, are formed 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. The annular flow passage PA1 includes not only a curve (annular flow passage curve to be described later) extending in the circumferential direction 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 changes in the circumferential direction. In other words, the annular flow passage PA1 only needs to 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 circumferential 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 and the annular flow path PA1 communicate with each other via the through hole 32a. The through hole 32a constitutes a supply flow path PA0 for the cooling medium.

[0020] The top of the stator core 20 communicating with the through hole 32a is the inlet portion 27, and a cooling medium is supplied to the annular flow passage 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 in the circumferential direction along the annular flow passage PA1. Furthermore, the cooling oil flows from the annular flow passage PA1 into the axial flow passage PA2 and flows in the axial direction along the axial flow passage PA2. This flow of cooling oil cools the stator core 20, and the coil 21 is cooled as the stator core 20 around the slots 22 is cooled. The cooling oil that has flowed through the axial flow passage PA2 flows out from both axial end faces of the stator core 20. As a result, the cooling oil is applied to the coil ends, facilitating the cooling of the coil 21.

[0021] Incidentally, the annular flow passage PA1 has an axial width W and a radial depth D and has a substantially rectangular cross-sectional shape. If the cross-sectional area of ​​the annular flow passage PA1 is constant over the entire circumference, the amount of cooling oil flowing out from the axial flow passage PA2 will differ in the circumferential direction. FIG. 3 is a diagram showing an example of the amount of cooling oil flowing out from each axial flow passage PA2. As shown in FIG. 3, the amount of cooling oil flowing out increases particularly near the top of the stator core 20. This is because cooling oil is supplied to the annular flow passage PA1 from the top (0°, 360°), and the pressure of the cooling oil in the annular flow passage PA1 increases closer to the top. The amount of cooling oil flowing out also decreases from the middle part (90°, 270°) in the height direction of the stator core 20 to the lowest part (180°). However, the degree of decrease in the amount of oil flowing out from the middle part in the height direction to the lowest part is smaller than the degree of decrease in the amount of oil flowing out from the top to the middle part in the height direction. In addition, due to the effect of gravity of the cooling oil, the outflow amount at the intermediate portion in the height direction may be less than the outflow amount at the lowest portion, and the outflow amount may be smallest at the intermediate portion in the height direction.

[0022] When a difference occurs in the flow rate of the cooling oil flowing through the axial flow passage PA2 in the circumferential direction in this manner, it becomes difficult for the flow of the cooling oil to uniformly cool the stator core 20 in the circumferential direction. Therefore, in this embodiment, the stator 2 for a rotating electric machine is configured as follows so that the stator core 20 is uniformly cooled in the circumferential direction.

[0023] Fig. 4 is a front view showing the main configuration of a single stator core constituting the rotating electric machine stator 2 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 recesses 24.

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

[0025] Therefore, the depth D of the annular flow passage PA1, which is calculated by subtracting the inner radius R2 from the outer radius R1, 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 all around. 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 outflow amount of cooling oil is small from the intermediate portion in the height direction of the stator core 20 to the bottom. In consideration of this point, although not shown, below the intermediate portion in the height direction of the stator core 20, the bottom surface 24a of the recess 24 is a cylindrical surface centered on the axis line CL0. Therefore, from the intermediate portion in the height direction of the stator core 20 to the bottom, 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 intermediate portion in the height direction, the inner radius R2 may be gradually decreased from the intermediate portion in the height direction to the bottom.

[0027] In this way, the cross-sectional area of ​​the annular flow passage PA1 gradually decreases from the top of the stator core 20 to the intermediate portion in the height direction, thereby preventing the pressure of the cooling oil from decreasing downstream of the supply passage PA0. This increases the amount of cooling oil flowing through the axial flow passage PA2 at the intermediate portion in the height direction of the stator core 20 and below it, and allows 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 called an annular flow passage curve showing the shape of the annular flow passage PA1. The annular flow passage curve C2 is not a circle centered on the axis CL0, but is gradually shifted radially outward from the top of the stator core 20 to the middle 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 middle 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 line CL0. Therefore, the inner radius R2 is constant over the entire circumference of the stator core 20, and the cross-sectional area of ​​the annular flow path PA1 is also constant.

[0030] 5, the multiple through holes 26 are arranged along a reference circle C1 centered on the axis CL0, but the diameter of the through holes 26 gradually decreases from the top to the middle in the height direction. For example, the diameter D2 of the through hole 26 at the middle in the height direction is about 1 / 2 the diameter D1 of the through hole 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 bottom. The diameter of the through holes 26 may be gradually decreased from the middle in the height direction to the bottom.

[0031] This makes it possible to suppress a gradual decrease in the cross-sectional area of ​​the axial flow passage PA2 and a decrease in the pressure of the cooling oil downstream of the supply flow passage PA0. As a result, the amount of cooling oil flowing through the axial flow passage PA2 increases at and below the intermediate portion in the height direction of the stator core 20, 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, the multiple through holes 26 are arranged along a reference circle C1 centered on the axis line CL0, but in Fig. 6, the multiple through holes 26 are arranged along a curve C3. This curve C3, like the annular flow passage curve C2 in Fig. 4, gradually shifts radially outward from the top of the stator core 20 to the middle in the height direction. Therefore, the distance (pitch diameter) from the axis line CL0 to the curve C3 is not constant, and the distance from the axis line CL0 to the top through hole 26 is longer than the distance from the axis line CL0 to the middle through hole 26 in the height direction.

[0033] In the above, the annular flow passage PA1 is formed by the recess 24 provided in the outer circumferential surface 20b of the stator core 20, but the annular flow passage PA1 may be formed by a through hole provided inside the stator core 20. Fig. 7 is a front view of the stator core 20 showing an example, and Fig. 8 is a view taken along the 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 the axial flow passage PA2 communicating with the annular flow passage PA1 is formed by the through holes 26 (see Fig. 1), but for convenience, the through holes 26 are not shown in Figs. 7 and 8. The stator core 20 is configured symmetrically with respect to a reference line L1 extending in the up-down direction.

[0034] As shown in Figs. 7 and 8, the stator core 20 is formed with a plurality of arc-shaped slit holes 28 centered on the axis CL0. More specifically, if the plurality of slit holes 28 from the top to the bottom of the stator core 20 are represented by slit holes 281 to 285, the circumferentially adjacent slit holes 28 are provided with positions shifted from each other in the axial direction as shown in Fig. 8. That is, the slit holes 281, 283, and 285 are provided in the first axial region AR1 (the electromagnetic steel sheet in the first region AR1), and the slit holes 282 and 284 are provided in the second axial region AR2 (the electromagnetic steel sheet in the second region AR2) adjacent to the first region AR1. Note that the slit holes 28 are not provided in the electromagnetic steel sheets on the outside of the first region AR1 and the second region AR2, and thus a slit-shaped space (division flow path) is formed inside the stator core 20.

[0035] 7, the slit holes 281-285 are provided so as to be shifted radially outward from the axis line CL0 as they move downward from the top. Therefore, the distance between the outer peripheral surface of the slit holes 281-285 and the outer peripheral surface of the stator core 20 is almost constant all around the stator core 20, whereas the distance between the outer peripheral end of the slot 22 and the inner peripheral surface of the slit holes 281-285 increases downward.

[0036] The slit holes 281-285 extend in the circumferential direction so 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 over the entire circumference via overlapping portions 29 at both circumferential ends. This allows the multiple divided flow paths to communicate with each other, and as a whole, forms an annular flow path PA1 centered on the axis line CL0. 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 the inlet portion 27, and the cooling oil is supplied to the annular flow path PA1 from the outside of the stator core 20 through the inlet portion 27.

[0037] As shown in FIG. 8, the width W1 (axial length) of the slit holes 281, 283, and 285 is equal to the width W2 (axial length) of the slit holes 282 and 284. These widths W1 and W2 are 1 / 2 of the width of the recess 24 in FIG. 4 to FIG. 6. As shown in FIG. 7, the radial width S of the slit holes 281 to 285 defines the radial length of the annular flow passage PA1 and corresponds to the depth D of the annular flow passage PA1 in FIG. 4 to FIG. 6. This width S is constant for each of the slit holes 281 to 285. However, when comparing the slit holes 281 to 285 with each other, the width S gradually becomes shorter from the top to the bottom. Therefore, the cross-sectional area of ​​the slit hole 281 at the top is maximum, and the cross-sectional area of ​​the slit hole 285 at the bottom is minimum, which suppresses the decrease in pressure of the cooling oil from the top to the bottom, and allows the cooling oil to flow evenly through the multiple axial flow passages 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 shortened 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 is gradually reduced from the top to the bottom of the stator core 20, but the cross-sectional area of ​​the slit holes 28 may be gradually reduced from the top to the middle in the height direction, and 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 be gradually reduced 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 embodiment. In FIG. 9, the reference example is an example in which the annular flow passage PA1 is formed in a single axial row by the recesses 24 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 over the entire circumference of the stator core 20, and the radius of the annular flow passage curve C2 is constant over the entire circumference. In this example, the flow rate of the cooling oil gradually decreases downward. In addition, since the generation of the magnetic path in the stator core 20 is blocked by the recesses 24, the motor torque decreases by a predetermined amount (for example, about 7%) compared to the case where the recesses 24 are not provided. The change in the motor torque is a value obtained by analysis.

[0041] The first embodiment is an example in which the radial width of the annular flow passage PA1 (depth D of the recess 24) gradually decreases downward, and the radius of the annular flow passage curve C2 is constant around the entire circumference of the stator core 20. In this example, the cross-sectional area of ​​the annular flow passage PA1 gradually decreases downward, so the flow rate of the cooling oil is almost constant around the entire circumference. Also, the range of the recess 24 is smaller than that in the reference example, so the degree of reduction in motor torque is also smaller than that in the reference example.

[0042] In the second embodiment, as shown in Fig. 4, the radial width of the annular flow passage PA1 is gradually decreased toward the bottom, and the annular flow passage curve C2 is gradually shifted radially outward toward the bottom. In this embodiment, the cross-sectional area of ​​the annular flow passage PA1 is gradually decreased toward the bottom, so the flow rate of the cooling oil is almost constant over the entire circumference. In addition, the range of the recess 24 is shifted radially outward more than in the first embodiment, so torque reduction is suppressed, and the degree of reduction in motor torque is smaller than in the first embodiment.

[0043] In the third embodiment, as shown in Fig. 5, the diameters of the axial passages PA2 are gradually decreased downward, and the axial passages PA2 are arranged along a reference circle C1 centered on the axis CL0. Therefore, the pitch diameters of the axial passages PA2 centered on the axis CL0 are constant over the entire circumference. In this example, the cross-sectional area of ​​the axial passages PA2 gradually decreases downward, so the flow rate of the cooling oil is almost constant over the entire circumference. In addition, the overall area of ​​the through holes 26 in the stator core 20 is reduced, so the degree of reduction in motor torque is also small.

[0044] As shown in Fig. 6, the fourth embodiment is an example in which the diameters of the axial passages PA2 are gradually decreased toward the bottom, and the axial passages PA2 are gradually shifted radially outward toward the bottom. Therefore, the pitch diameters of the axial passages PA2 centered on the axis CL0 are gradually increased toward the bottom. In this example, the cross-sectional area of ​​the axial passages PA2 is gradually decreased toward the bottom, so that the flow rate of the cooling oil is almost constant over the entire circumference. In addition, the through holes 26 are shifted radially outward, so that torque reduction is suppressed, and the degree of reduction in motor torque is smaller than that of the third embodiment.

[0045] In the fifth embodiment, as shown in Fig. 7, an annular flow passage PA1 is formed in two axial rows by slit holes 28, the radial width of the annular flow passage PA1 is gradually decreased downward, and the annular flow passage curve C2 is gradually shifted outward downward. In this example, the cross-sectional area of ​​the annular flow passage PA1 is gradually decreased downward, so the flow rate of the cooling oil is almost constant around the entire circumference. In addition, the range of the recessed portion 24 is shifted outward in the radial direction, so the degree of reduction in motor torque is small.

[0046] According to this embodiment, the following advantageous effects can be obtained. (1) The stator 2 for a rotating electric machine includes a stator core 20 in which a plurality of slots 22 are provided in the circumferential direction around an axis CL0 extending in a substantially horizontal direction, and a coil 21 arranged in the slot 22 (FIG. 1). The stator core 20 has an annular flow passage PA1 having a substantially circular shape centered on the axis CL0, to which cooling oil is introduced via an inlet portion 27, and a plurality of circumferential axial flow passages PA2 communicating with the annular flow passage PA1 and extending in the axial direction (FIGS. 1 and 2). At least one of the annular flow passage PA1 and the plurality of axial flow passages PA2 is formed so that the flow passage cross-sectional area becomes smaller with increasing distance from the inlet portion 27 (FIGS. 4 and 5). This increases the pressure of the cooling oil downward compared to when the flow passage cross-sectional area is constant in the circumferential direction. As a result, the cooling oil can be made to flow uniformly in the circumferential direction around the stator core 20, 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 becomes smaller with increasing distance from the inlet portion 27, and the distance from the axis CL0 to the annular flow passage PA1 becomes longer with increasing distance from the inlet portion 27, that is, the annular flow passage curve C2 is shifted downward and radially outward (FIG. 4). This makes it possible to prevent the recess 24 from interfering with the magnetic path of the stator core 20, and to prevent 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 uniformly cooled in the circumferential direction. In addition, a decrease in motor torque can be suppressed.

[0049] (4) The annular flow passage PA1 is formed so that the flow passage cross-sectional area becomes smaller with increasing distance from the inlet portion 27, and is composed of a plurality of slit holes 281-285 (divided flow passages) having a substantially arc shape including slit holes 281, 283, 285 (first divided flow passage) and slit holes 282, 284 (second divided flow passage) adjacent to each other in the circumferential direction (FIG. 7). The slit holes 281, 283, 285 and the slit holes 282, 284 are provided with their positions shifted in the axial direction (FIG. 8). This makes it possible to form the annular flow passage PA1 inside the stator core 20 in such a way that the flow rate is prevented from decreasing downward without using the inner circumferential surface 31 of the case 3 (FIG. 1).

[0050] (5) The inlet portion 27 is provided at the upper portion of the annular flow passage PA1 that extends from the upper portion to the middle portion and the lower portion 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 upper portion to the middle portion (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 upper portion (top) to the middle portion of the stator core 20 is particularly large (FIG. 3).

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

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

[0053] In the above embodiment, the cooling oil is supplied to the cooling flow passage, but the cooling medium is not limited to the cooling oil. In the above embodiment, the rotor 1 is disposed radially inside the stator 2, but the rotor may be disposed radially outside the stator. In the above embodiment, the stator for a rotating electric machine is applied to a vehicle, but the stator for a rotating electric machine of the present invention may also be applied to other applications besides vehicles.

[0054] The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications, as long as the features of the present invention are not impaired. The above-mentioned embodiment and one or more modifications can be arbitrarily combined, and modifications can be combined with each other. [Explanation of symbols]

[0055] 2 stator, 20 stator core, 21 coil, 22 slot, 24 recess, 27 inlet, 28 slit hole, 281-285 slit holes, PA1 annular flow passage, PA2 axial flow passage

Claims

1. a stator core having a plurality of slots provided in a circumferential direction around an axis extending in a substantially horizontal direction; A stator for a rotating electric machine comprising: The stator core is a first flow passage having a substantially annular shape centered on the axis line, into which cooling oil is introduced via an inlet portion; a plurality of second flow passages extending in the axial direction and in communication with the first flow passage; a first passage and / or a plurality of second passages each having a cross-sectional area that decreases with increasing distance from the inlet portion;

2. 2. The stator for a rotating electric machine according to claim 1, a first flow passage formed so that a flow passage cross-sectional area becomes smaller with increasing distance from the inlet portion, and a distance from the axis to the first flow passage becomes longer with increasing distance from the inlet portion.

3. 2. The stator for a rotating electric machine according to claim 1, a stator for a rotating electric machine, characterized in that the plurality of second flow paths are formed so that a flow path cross-sectional area becomes smaller as the flow path moves away from the inlet portion, and a distance from the axis to the plurality of second flow paths becomes longer as the flow path moves away from the inlet portion.

4. The stator for a rotating electric machine according to any one of claims 1 to 3, the first flow passage has a plurality of substantially arc-shaped divided flow passages including a first divided flow passage and a second divided flow passage adjacent to each other in a circumferential direction, The stator for a rotating electric machine, wherein the first divided passage and the second divided passage are provided at positions shifted from each other in the axial direction.

5. The stator for a rotating electric 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, a first flow passage formed so that a cross-sectional area of ​​the first flow passage gradually decreases from the upper portion to the middle portion of the stator core;

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