Cooling structure for electric motor

Abstract

To improve cooling performance of a stator provided with a coil.SOLUTION: In a cooling structure of an electric motor, a stator yoke 9 is formed with a slot that opens toward an inner peripheral side thereof and continues in an axial direction, a coil is held inside the slot, and a stator 3 in which a coil end 10 protrudes to both end sides in the axial direction of the stator yoke 9 is cooled by cooling fluid C. An inlet 11 for introducing the cooling fluid C radially outward of the coil end 10 is provided at one end of the stator yoke 9 in the axial direction, a cooling passage 14 for flowing the cooling fluid C is formed from one end of the stator yoke 9 in the axial direction toward the other end, at a position closer to the slot than an outer surface of the stator yoke 9, one end of the cooling passage 14 is connected to the inlet 11 of the stator yoke 9, and the other end of the cooling passage opens on the other end side of the stator yoke 9.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a structure for cooling a stator that holds a coil in an electric motor by supplying a cooling fluid such as oil to the stator.

Background Art

[0002] A device for cooling a motor is described in Patent Document 1. The device is configured to perform cooling by flowing a cooling fluid in the axial direction inside a stationary core. That is, the stationary core is formed by laminating a large number of annular electromagnetic steel sheets. On the inner peripheral side thereof, a plurality of teeth extending toward the center of the stationary core are provided, and coils are held in the slots between those teeth. A plurality of cooling channels for allowing the cooling fluid to flow are formed side by side in the circumferential direction in the outer peripheral portion of the stationary core, which is greatly separated radially outward from the slots of the stationary core. That is, by drilling through holes in the outer peripheral portion of the electromagnetic steel sheet and laminating the electromagnetic steel sheets so that those through holes are connected in the axial direction, the cooling channels are formed by those through holes. Further, each electromagnetic steel sheet has a convex portion protruding radially outward, and by laminating the electromagnetic steel sheets, a so-called bead-shaped raised portion extending in the axial direction is formed on the outer peripheral portion of the stationary core by that convex portion. Inside the raised portion, bolt holes for passing bolts for fastening or fixing the electromagnetic steel sheets are provided along the axial direction, and an inflow hole is provided in parallel therewith. An arcuate groove or slit centered on the center of the stationary core is formed at the position of the outer peripheral portion of the electromagnetic steel sheet located substantially at the center in the axial direction of the stationary core with respect to the cooling channel, and that groove or slit serves as a header for each cooling channel. Further, a communication portion for communicating the groove or slit with the inflow hole is formed. Therefore, when the cooling fluid is supplied to the inflow path by a pump or the like, the cooling fluid is dispersed and supplied to each cooling channel through the above-described communication path and the above-described groove or slit at substantially the center in the axial direction of the stationary core. The cooling fluid flows in both axial directions from substantially the center in the axial direction of the stationary core, flows out of the cooling channel at the end of the stationary core, and falls on the coil end. That is, substantially the center in the axial direction of the cooling channel serves as the inflow portion of the cooling fluid, and both axial ends serve as the outflow portions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] The temperature of the stationary core rises due to Joule heat generated by passing an electric current through the coil or due to a change in magnetic flux. The heat is transmitted to the outer peripheral side of the electromagnetic steel sheet and reaches the cooling flow path, and is carried to the outside by the cooling fluid flowing through here. That is, the stationary core is cooled from its outer peripheral portion side by the cooling fluid. However, the heat generation in the stationary core is mainly caused by the coil, whereas in the configuration described in Patent Document 1 above, since cooling is performed at the outer peripheral portion away from the coil, there is a possibility that the temperature of the stationary core may increase due to heat storage between the coil or the teeth holding the coil and the cooling flow path. In other words, the thermal resistance from the coil to the cooling fluid is large, and there is room for improvement in terms of the cooling effect.

[0005] In addition, with the cooling flow path provided in the outer peripheral portion of the stationary core, the outflow portion of the cooling fluid directed toward the coil end is located far above the coil end. As a result, the coverage rate of the coil end by the cooling fluid is low, and there is a possibility that the coil end may not necessarily be sufficiently cooled.

[0006] The present invention has been made paying attention to the above technical problems, and an object thereof is to provide a cooling structure for an electric motor capable of improving the cooling performance of a stator provided with a coil.

MEANS FOR SOLVING THE PROBLEMS

[0007] In order to achieve the above object, the present invention provides a cooling structure for an electric motor that cools a stator in which a slotted stator yoke formed by laminating annular steel plates has slots that open toward the inner peripheral side and are continuous in the axial direction, a coil is held inside the slots, and coil ends project to both ends in the axial direction of the stator yoke, by a cooling fluid. The cooling structure is characterized in that an inlet for introducing the cooling fluid is provided at one end in the axial direction of the stator yoke and radially outside the coil end, a cooling flow path for flowing the cooling fluid is formed from one end side to the other end side in the axial direction of the stator yoke at a position closer to the slots than the outer peripheral surface of the stator yoke, one end of the cooling flow path communicates with the inlet of the stator yoke, and the other end of the cooling flow path opens to the other end side of the stator yoke.

[0008] In the present invention, the opening shape of the cooling flow path may be a shape in which a dimension measured in the circumferential direction of the stator yoke is smaller than a dimension measured in the radial direction of the stator yoke.

[0009] In the present invention, the opening shape of the inlet may be a shape in which a dimension measured in the radial direction of the stator yoke is smaller than a dimension measured in the circumferential direction of the stator yoke.

[0010] In the present invention, a header portion, which is an annular cavity that covers the inlet at one end side in the axial direction of the stator yoke and distributes and supplies the cooling fluid to each of the inlets, is provided, and an outflow hole for supplying the cooling fluid to the coil end that projects to one end side in the axial direction of the stator yoke may be formed in the header portion.

[0011] In the present invention, a third steel plate sandwiched between a first steel plate provided with the inlet and a second steel plate formed with the cooling flow path is provided, and a communication hole portion that opens to both the inlet provided in the first steel plate and the cooling flow path provided in the second steel plate is formed in the third steel plate, and the inlet and the cooling flow path may be communicated with each other by the communication hole portion.

Effect of the Invention

[0012] According to the present invention, since the inlet for supplying the cooling fluid to the inside of the stator yoke is provided on the outer peripheral side rather than the coil end, it is possible to avoid interference between the inlet and the coil end and increase the size of the inlet shape as needed, etc., and there is an advantage that the degree of freedom in designing the inlet shape increases. Further, since the cooling flow path through which the cooling fluid flows inside the stator yoke is provided at a position closer to the slot than the outer peripheral surface of the stator yoke, that is, at a position closer to the coil, it will be cooled by the cooling fluid at a position close to the coil that generates heat when operating. That is, the thermal resistance between the coil and the cooling fluid is small, and as a result, it becomes possible to effectively cool the stator yoke. Furthermore, since the opening end of the cooling flow path, that is, the outlet, is located at a position close to the coil end at the other end in the axial direction of the stator yoke, the cooling fluid flows down without coming off from the coil end, and as a result, the oil coverage rate can be improved. Thus, according to the present invention, since the cooling fluid carries away a lot of heat, the cooling performance of the stator can be improved.

[0013] The opening shape of the cooling flow path of the present invention, that is, the shape when cut by a plane perpendicular to the central axis of the stator yoke, has a small dimension in the circumferential direction. The location where this cooling flow path is provided is a location close to the slot (teeth forming the slot), and is a location where the magnetic flux is directed in the radial direction of the stator yoke or a direction close thereto. Therefore, the width or area in which the cooling flow path blocks the magnetic flux becomes small, and deterioration or reduction of magnetic characteristics can be suppressed.

[0014] Similarly, the opening shape of the inlet of the present invention, that is, the shape when cut by a plane perpendicular to the central axis of the stator yoke, has a small dimension in the radial direction. The location where this inlet is provided is a portion on the outer peripheral side of the stator yoke, where the magnetic flux is directed in the circumferential direction of the stator yoke or a direction close thereto. Therefore, since the width or area by which the inlet blocks the magnetic flux is small, it is possible to suppress the deterioration or decrease of the magnetic characteristics due to the inlet.

[0015] In the present invention, the header portion is formed as an annular cavity facing each inlet arranged in the circumferential direction at the axial end of the stator yoke. Therefore, by supplying the cooling fluid to the header portion, the cooling fluid can be distributed and supplied to the cooling channels respectively communicating with all the inlets. Moreover, the cooling fluid can be dripped from the outflow holes to the coil ends located on the inner peripheral side of the header portion to cool the coil ends.

[0016] In the present invention, holes are drilled through the ring-shaped steel plate in the plate thickness direction, and the steel plates are laminated so that these holes communicate with each other, whereby the inlet, the cooling channel, and the communication hole portion can be formed. Therefore, processing and assembly become easy, and since there is no particular need for a portion protruding to the outside, the overall shape can be simplified.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0018] Next, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiments described below are merely examples of implementing the present invention and do not limit the present invention.

[0019] The overall configuration of the motor 1 in the embodiment of the present invention is schematically shown in FIG. 1. The example shown here is a permanent magnet type synchronous motor, and except for the structure for cooling, its basic configuration is substantially the same as that of a conventional motor. That is, a cylindrical stator 3 is arranged concentrically on the outer peripheral side of the rotor 2. The rotor 2 holds permanent magnets (not shown), and a rotor shaft 4 protruding on both sides in the axial direction thereof is rotatably held by a motor case 6 via bearings 5. The motor case 6 is a hollow member that covers the entire motor 1, and the above-mentioned stator 3 is fixed to its inner peripheral surface.

[0020] The stator 3 is composed of a large number of annular thin electromagnetic steel sheets laminated. As partially shown in FIG. 2, slots 7 opening toward the inner peripheral side are formed side by side in the circumferential direction at the inner peripheral portions of the respective electromagnetic steel sheets, and the portions between those slots 7 become teeth 8. The electromagnetic steel sheets are laminated with their postures aligned so that the slots 7 or the teeth 8 are arranged in the direction of the central axis of the stator 3, and thus a stator yoke (fixed core) 9 is formed. For example, coils connected in series for each of the three phases are arranged in each slot 7, and the folded end portions (coil ends) 10 thereof protrude from both ends in the axial direction of the stator yoke 9.

[0021] In the cooling structure according to the embodiment of the present invention, the stator yoke 9 configured as described above is configured to cool the electric motor 1 (particularly the stator 3 and the coil end 10) by flowing the cooling fluid C inside the stator yoke 9. More specifically, FIG. 3 schematically shows a part of both ends of the stator yoke 9 in the axial direction. A plurality of electromagnetic steel sheets 9a located at the right end of FIG. 3 among the electromagnetic steel sheets constituting the stator yoke 9 have through holes penetrating in the plate thickness direction, and the inlet 11 is formed by these through holes. As shown in FIG. 2, the inlet 11 is formed on the outer peripheral side of the electromagnetic steel sheet (stator yoke 9), more specifically, on the outer peripheral side of the coil end 10 so as not to interfere with the aforementioned coil end 10. Further, the inlet 11 is, for example, a through portion having an opening width smaller than the maximum width of the teeth 8, and a plurality of inlets 11 are formed at predetermined intervals in the circumferential direction on the outer peripheral portion of the electromagnetic steel sheet (stator yoke 9). The electromagnetic steel sheet 9a provided with the inlet 11 corresponds to the first steel sheet in the embodiment of the present invention.

[0022] Since the inlet 11 is provided on the outer peripheral side of the coil end 10, there is little room for interference with the coil end 10. Therefore, its opening area (size) and shape can be appropriately set as needed. That is, the degree of freedom in design is high, including the shape of the inlet 11. Further, the opening shape of the inlet 11 (cross-sectional shape when cut by a plane perpendicular to the central axis of the stator yoke 9) can be appropriately determined as needed, but considering the direction of the magnetic flux 12 generated in the stator yoke 9, it is preferably the shape described below.

[0023] FIG. 4 shows, by curves, the direction of magnetic flux 12 when the stator yoke 9 (electromagnetic steel sheet) is viewed from the axial direction. In the portion on the outer peripheral side of the teeth 8, the magnetic flux 12 is generated so as to connect the teeth 8 across the slots 7. In the portion of the teeth 8, the magnetic flux 12 is generated in the longitudinal direction thereof (the radial direction of the electromagnetic steel sheet or the stator yoke 9). Since the inlet 11 is a hollow portion through which the cooling fluid C flows, it acts to reduce the portion where the magnetic flux 12 is generated (or flows) and to block the magnetic flux 12. Considering such a direction of the magnetic flux 12, the opening shape of the inlet 11 is preferably a rectangle, an ellipse, a rhombus, or the like in which the dimension in the radial direction is smaller than the dimension in the circumferential direction (or the direction perpendicular to the radial direction) in order to make the cross-sectional area perpendicular to the direction of the magnetic flux 12 (the area facing the magnetic flux 12) small while ensuring the area as the flow path of the inlet 11. By doing so, while ensuring the cross-sectional area of the flow path of the cooling fluid C, the influence on the magnetic flux 12 can be reduced, and the deterioration of the magnetic characteristics or the performance of the motor 1 can be avoided or suppressed.

[0024] In a plurality of other electromagnetic steel sheets 9b adjacent to the electromagnetic steel sheet in which the through portion constituting the above-described inlet 11 is formed, through portions that are long in the radial direction of the electromagnetic steel sheet 9b are formed, and communication hole portions 13 are formed by laminating the electromagnetic steel sheets so that the through portions overlap in the axial direction. The communication hole portions 13 are provided corresponding to the above-described inlets 11. That is, the communication hole portions 13 are provided at the same positions as the inlets 11 in the circumferential direction of the electromagnetic steel sheet. Further, the outer peripheral side (outer side in the radial direction of the electromagnetic steel sheet) ends of the respective communication hole portions 13 overlap the inlets 11. That is, each of the plurality of communication hole portions 13 communicates with the above-described inlet 11. The electromagnetic steel sheet 9b in which the communication hole portions 13 are formed corresponds to the third steel sheet in the embodiment of the present invention.

[0025] A cooling channel 14 for flowing a cooling fluid C supplied from an inlet 11 through the above-described communication hole portion 13 is formed inside the stator yoke 9. That is, through holes penetrating in the plate thickness direction are formed in the electromagnetic steel plate 9c from the electromagnetic steel plate in contact with the electromagnetic steel plate 9b in which the above-described communication hole portion 13 is formed to the other end portion (the left end in FIG. 3) of the stator yoke 9, and the cooling channel 14 is formed by laminating the electromagnetic steel plates so that these through holes overlap each other. The electromagnetic steel plate 9c in which the cooling channel 14 is formed corresponds to the second steel plate in the embodiment of the present invention that sandwiches the electromagnetic steel plate 9b corresponding to the above-described third steel plate between the electromagnetic steel plate 9a corresponding to the above-described first steel plate.

[0026] This cooling channel 14 is provided at a position closer to the above-described slots 7 or teeth 8 than the outer peripheral surface of the electromagnetic steel plate or the stator yoke 9. For example, as shown in FIG. 2, a part of the inner peripheral side enters the teeth 8 and is provided at a position overlapping the slots 7 when viewed in the circumferential direction. Further, the opening end of the cooling channel 14 on one end side (the right end side in FIG. 3) in the axial direction of the stator yoke 9 is located corresponding to the inner end portion in the radial direction of the above-described communication hole portion 13. That is, the cooling channels 14 are provided side by side in the circumferential direction in the same number as the teeth 8, and each cooling channel 14 communicates with the communication hole portion 13. Therefore, the above-described inlet 11 and one end portion of the cooling channel 14 are connected through the communication hole portion 13. Further, the other end portion (the left end in FIG. 3) of the cooling channel 14 opens to the side surface of the stator yoke 9 and serves as an outlet 15. Therefore, this outlet 15 is arranged close to the coil end 10, such as directly above the coil end 10, and the outflowing cooling fluid C falls onto the coil end 10.

[0027] The opening shape of these cooling channels 14 (the cross-sectional shape when cut by a plane perpendicular to the central axis of the stator yoke 9) can be appropriately determined as needed, similar to the above-described inlet 11. However, considering the direction of the magnetic flux 12 generated in the stator yoke 9, it is preferably the shape described below. As described with reference to FIG. 4, in the portion close to the teeth 8, the direction of the magnetic flux 12 is in the longitudinal direction of the teeth 8 (the radial direction of the electromagnetic steel sheet or the stator yoke 9) or a direction close thereto. Further, the cooling channel 14 is a hollow portion through which the cooling fluid C flows, and since it reduces the portion where the magnetic flux 12 is generated (or flows) and acts to block the magnetic flux 12, the opening shape of the cooling channel 14 is such that the cross-sectional area perpendicular to the direction of the magnetic flux 12 (the area facing the magnetic flux 12) is made small while ensuring the area of the cooling channel 14 as a flow path. Therefore, as shown in FIG. 2, it is preferably a shape such as a rectangle, an ellipse, or a rhombus (a so-called vertically long shape in FIG. 2) whose dimension in the circumferential direction is smaller than the dimension in the radial direction. By doing so, while ensuring the flow path cross-sectional area of the cooling fluid C, the influence on the magnetic flux 12 can be reduced, and a decrease in magnetic characteristics or the performance of the motor 1 can be avoided or suppressed.

[0028] Note that the above-described communication hole portion 13 only needs to function to connect the inlet 11 and the cooling channel 14, so the opening shape can be appropriately set within that range. FIG. 2 shows a trapezoidal communication hole portion 13 with a narrow width on the inner peripheral side. However, in addition to this, for example, as shown in FIG. 5, a shape 13A in which the outer peripheral side portion is enlarged and the inner peripheral side portion is narrowed, a T-shaped 13B, etc. may also be used.

[0029] Next, a configuration for supplying the cooling fluid C to each inlet 11 will be described. On the end face of the stator yoke 9 where each inlet 11 is open, a header portion 16, which is a cavity covering each inlet 11, is provided. That is, the header portion 16 is configured as an annular cavity partitioned by a guide member 17 disposed between the inlet 11 and the coil end 10 and a part of the motor case 6. The guide member 17 is generally cylindrical and is sandwiched between the side surface of the electromagnetic steel sheet (the rightmost electromagnetic steel sheet in FIG. 3) where the inlet 11 is formed and the inner side surface of the motor case 6 facing the side surface. A sealing material such as an O-ring is interposed between both the side surface of the electromagnetic steel sheet and the inner side surface of the motor case 6 to achieve a liquid-tight state. Therefore, the outer peripheral side portion of the cylindrical portion 17a in the guide member 17 forms the header portion 16, which is a closed cavity together with the motor case 6, and each inlet 11 opens toward this header portion 16.

[0030] And a pump 18 for supplying the cooling fluid (for example, oil) C to this header portion 16 is connected. In the cylindrical portion 17a of the guide member 17, an outflow hole 19 for supplying the cooling fluid C toward the coil end 10 on its inner peripheral side is formed. Also, the header portion 16 may communicate with the gap between the outer peripheral surface of the stator yoke 9 and the inner peripheral surface of the motor case 6, or conversely, it may be in a liquid-tight state. To achieve a liquid-tight state, an appropriate sealing material such as an O-ring may be interposed between the end face in the axial direction of the stator yoke 9 and the motor case 6.

[0031] Next, the operation of the above-described cooling structure will be described. When an electric current is passed through the coil to rotate the electric motor 1, or when the rotor 2 is forcibly rotated by an external force to cause the electric motor 1 to function as a generator, heat is generated in the coil. Further, heat is generated due to the change in magnetic flux in the stator yoke 9. In that case, when the cooling fluid C such as oil is supplied to the header portion 16 by the pump 18, the cooling fluid C is dispersed and supplied to the inlet 11 that opens toward the header portion 16. The cooling fluid C is sent through the communication hole portion 13 to the cooling flow path 14 that extends in the axial direction inside the stator yoke 9. Since the cooling flow path 14 is provided at a position close to the slot 7 or the coil as described above, the cooling fluid C flows near the coil with a large calorific value and takes heat from around it. That is, since the coil and the cooling fluid C are close to each other and the thermal resistance between them is small, the coil can be efficiently cooled through the stator yoke 9.

[0032] In this way, the cooling fluid C takes heat to cool the coil and the stator yoke 9 while flowing toward the other end in the axial direction of the stator 3, and flows out from the outlet 15 at the other end. Since the cooling flow path 14 is formed at a position close to the coil as described above, the outlet 15, which is the open end thereof, is also close to the coil end 10. Therefore, the cooling fluid C ejected from the outlet 15 immediately strikes the coil end 10, and the coverage rate of the coil end 10 by the cooling fluid C becomes high. That is, the cooling fluid C can be efficiently sprayed onto the coil end 10 to take heat from the coil end 10 and cool it.

[0033] On the other hand, a part of the cooling fluid C supplied to the header portion 16 is supplied from the outflow hole 19 provided in the cylindrical portion 17a of the guide member 17 constituting the header portion 16 toward the coil end 10 on the inner peripheral side of the cylindrical portion 17a. As a result, both coil ends 10 protruding on both sides in the axial direction of the stator 3 are cooled by the cooling fluid C.

[0034] The cooling fluid C supplied toward each coil end 10 flows downward under the electric motor 1 and then returns to a storage section such as an oil pan (not shown). Thereafter, it is pumped up again by a pump 18 and supplied to the header section 16 described above. Since the cooling fluid C is circulated in this way, it is preferable to provide a radiator (or cooler) in the middle of the circulation path to cool the cooling fluid C.

[0035] The above-described cooling fluid C is, for example, oil and functions to block the magnetic flux 12. However, as described above, the inlet 11 and the cooling flow path 14 filled with the cooling fluid C are configured such that the area (or projected area) of the plane perpendicular to the direction of the magnetic flux 12 is smaller than the area in the direction parallel to the direction of the magnetic flux 12. Therefore, the blocking or shielding of the magnetic flux 12 caused by providing the inlet 11 and the cooling flow path 14 can be suppressed as much as possible while ensuring the flow path cross-sectional areas of the inlet 11 and the cooling flow path 14. That is, with the above-described configuration, it is possible to avoid or suppress a decrease in the magnetic characteristics of the stator 3 or the performance of the electric motor 1.

[0036] In addition, the above-described inlet 11, communication hole portion 13, and cooling flow path 14 can be configured by, for example, punching through holes in the electromagnetic steel sheets constituting the stator yoke 9 and laminating the electromagnetic steel sheets so that the through holes coincide with each other. Since the operation of punching the through holes and the operation of laminating the electromagnetic steel sheets are not particularly different from the conventional manufacturing operations of the stator, according to the embodiment of the present invention, it is possible to easily obtain a stator 3 or an electric motor 1 having excellent cooling effects. In other words, it is possible to inexpensively obtain an electric motor 1 having excellent thermal characteristics.

[0037] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented within the scope that produces the above-described operations and effects. For example, the communication hole portion in the present invention, in addition to being configured as a hole portion continuous in the radial direction of the stator yoke, a hole portion extending to the middle of the cooling flow path 14 from the inlet 11 is formed in a predetermined electromagnetic steel sheet, and in another electromagnetic steel sheet adjacent thereto, another hole portion leading from the hole portion to the cooling flow path 14 is formed, and the communication hole portion may be constituted by these two hole portions. Further, the shape of the guide member 17 constituting the header portion 16 may be an appropriate shape according to the shape inside the motor case 6. Furthermore, the steel sheet provided with the inlet or the steel sheet provided with the communication hole portion may be a steel sheet other than the electromagnetic steel sheet.

Description of Reference Numerals

[0038] 1 Electric motor 2 Rotor 3 Stator 4 Rotor shaft 5 Bearing 6 Motor case 7 Slot 8 Teeth 9 Stator yoke 9a, 9b, 9c Electromagnetic steel sheet 10 Coil end 11 Inlet 12 Magnetic flux 13 Communication hole portion 14 Cooling flow path 15 Outlet 16 Header portion 17 Guide member 17a Cylindrical portion 18 Pump 19 Outflow hole C Cooling fluid

Claims

1. A cooling structure for an electric motor that cools a stator in which a slot that opens toward the inner peripheral side and is continuous in the axial direction is formed in a stator yoke formed by laminating annular steel plates, a coil is held inside the slot, and coil ends protrude to both end sides in the axial direction of the stator yoke with a cooling fluid, wherein: an inlet for flowing the cooling fluid is provided at one end portion of the stator yoke in the axial direction and radially outside the coil end; a cooling flow path for flowing the cooling fluid is formed at a position closer to the slot than the outer peripheral surface of the stator yoke, from one end side to the other end side in the axial direction of the stator yoke; one end of the cooling flow path communicates with the inlet of the stator yoke, and the other end of the cooling flow path opens to the other end side of the stator yoke. A cooling structure for an electric motor, characterized by the above.

2. A cooling structure for an electric motor according to claim 1, wherein: the opening shape of the cooling flow path is a shape in which a dimension measured in the circumferential direction of the stator yoke is smaller than a dimension measured in the radial direction of the stator yoke. A cooling structure for an electric motor, characterized by the above.

3. A cooling structure for an electric motor according to claim 1, wherein: the opening shape of the inlet is a shape in which a dimension measured in the radial direction of the stator yoke is smaller than a dimension measured in the circumferential direction of the stator yoke. A cooling structure for an electric motor, characterized by the above.

4. A cooling structure for an electric motor according to any one of claims 1 to 3, wherein: a header portion, which is an annular cavity that covers the inlet at one end side of the stator yoke in the axial direction and distributes and supplies the cooling fluid to each of the inlets, is provided; outlet holes for supplying the cooling fluid are formed in the header portion for the coil ends that protrude to one end side of the stator yoke in the axial direction. A cooling structure for an electric motor, characterized by the above.

5. A cooling structure for an electric motor according to any one of claims 1 to 3, wherein: it includes a third steel plate sandwiched between a first steel plate provided with the inlet and a second steel plate in which the cooling flow path is formed; communication hole portions that open to both the inlet provided in the first steel plate and the cooling flow path provided in the second steel plate are formed in the third steel plate. The inlet and the cooling flow path are communicated with each other through the communication hole portion. A cooling structure for an electric motor, characterized by the above.

Images