stata

Abstract

In some cases, sufficient cooling effect could not be obtained in the lower range of the coil end where the heated refrigerant flows down. [Solution] A stator in which a coil is cooled by a refrigerant, comprising: a cylindrical stator core having a plurality of teeth protruding radially toward the inner circumference and oriented horizontally or substantially horizontally in the axial direction; a coil wound around the plurality of teeth and extending along the circumferential direction of the stator core, including a coil end portion that protrudes outward from the end face of the stator core in the axial direction; a plurality of refrigerant flow paths, each penetrating the stator core in the axial direction and capable of supplying refrigerant to the coil end portion from each opening on the end face of the stator core, formed at intervals along the circumferential direction; and a plurality of refrigerant guide portions provided at multiple positions on the coil end portion to discharge the refrigerant flowing down along the coil end portion to the radially outer circumference of the stator core.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a stator in which a coil is cooled by a refrigerant.

Background Art

[0002] There is known a stator in which a coil is wound around a plurality of teeth protruding from the inner peripheral side of a cylindrical stator core. A rotatable rotor is disposed inside the stator core, and such a rotor and stator constitute a motor.

[0003] Patent Document 1 describes that a motor including a stator is mounted, for example, as a power source of a vehicle, with its axis substantially along the horizontal direction. According to this document, cooling oil flows down from above and is supplied to the stator, and the stator including the coil is cooled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above-described coil has a coil end portion that protrudes outward from the end surface of the stator core in the axial direction of the stator core. The refrigerant supplied to the coil end portion for cooling flows down while traveling along the annularly extending coil end portion. In this case, the refrigerant flowing on the surface of the coil end portion gradually increases in temperature as it receives heat from the coil during the flowing-down process. Therefore, there is a possibility that a sufficient cooling effect by the refrigerant cannot be obtained in the lower range where the thus-heated refrigerant flows down in the coil end portion.

Means for Solving the Problems

[0006] This specification discloses a stator in which a coil is cooled by a refrigerant. The stator comprises a cylindrical stator core having a plurality of teeth protruding radially inward and oriented horizontally or substantially horizontally in its axial direction; a coil wound around the plurality of teeth and extending along the circumferential direction of the stator core, the coil including a coil end portion that protrudes outward from the end face of the stator core in the axial direction; a plurality of refrigerant flow paths, each penetrating the stator core along the axial direction and capable of supplying the refrigerant to the coil end portion from each opening in the end face of the stator core, and formed at intervals along the circumferential direction; and a plurality of refrigerant guide portions provided at multiple positions of the coil end portion and discharging the refrigerant flowing down the coil end portion to the radially outer circumferential side of the stator core.

[0007] According to the above configuration, the refrigerant that has absorbed heat as it flows down along the coil end portion extending circumferentially to the stator core is discharged to the radially outer side of the stator core by the refrigerant guide portion. Therefore, in the area of ​​the coil end portion located below the refrigerant guide portion, the refrigerant that has absorbed heat and is flowing down and the refrigerant newly supplied to that area mix, preventing the overall temperature of the refrigerant from rising. As a result, the cooling effect of the refrigerant on the coil end portion can be improved compared to conventional methods. [Brief explanation of the drawing]

[0008] [Figure 1] A simplified perspective view showing the structure of the stator. [Figure 2] A simplified diagram showing the stator from a direction perpendicular to the axis of the stator core. [Figure 3] A simplified diagram showing the end faces of the stator core from the axial direction. [Figure 4] A perspective view showing the refrigerant guide section and a portion of the coil end section before installation. [Figure 5] A perspective view showing the refrigerant guide attached to a portion of the coil end. [Figure 6]A diagram showing a conventional stator from the same viewpoint as Figure 3. [Modes for carrying out the invention]

[0009] This embodiment will be described with reference to the drawings. Each figure is for illustrative purposes only, and this embodiment is not limited to what is shown. Also, since each figure is illustrative, some parts may be omitted.

[0010] Figure 1 shows a simplified perspective view of the structure of a stator 10 in which the coils are cooled by a refrigerant. The refrigerant is described as a cooling oil such as ATF (Automatic Transmission Fluid®), but other refrigerants (e.g., coolant) may also be used. The refrigerant may also be called a coolant. The stator 10 comprises a stator core 11 and coils 12. The stator 10 is a component of a motor driven by electric power. The concept of a motor includes various types of motors, such as DC (direct current) motors, AC (alternating current) motors, stepping motors, and servo motors.

[0011] The specific configuration and material of the stator core 11 are not particularly limited. For example, the stator core 11 is generally cylindrical and is constructed by laminating multiple silicon steel plates. Hereinafter, the radial direction, circumferential direction, and axial direction of the stator core 11 will be simply referred to as the radial direction, circumferential direction, and axial direction, respectively. On the inner circumference of the stator core 11, multiple teeth portions 13 are projected toward the radially inner circumference. The multiple teeth portions 13 are arranged along the circumferential direction. The gaps between adjacent teeth portions 13 in the circumferential direction are called slots. All of the multiple slots open to the inner circumferential surface and the axially facing end face 14 of the stator core 11.

[0012] The coil 12 is wound around multiple teeth 13 and extends along the circumference. There are various ways in which the coil 12 is wound around the teeth 13, so it is not particularly limited here. The coil 12 is constructed by connecting multiple conductive wires having a rectangular cross-section, called segment coils, which are roughly U-shaped. For example, the coil 12 is constructed by inserting two legs of a segment coil into adjacent or separated slots in the circumference from one side in the axial direction, and bending the leg of the segment coil protruding from the other side in the axial direction in at least one of the circumferential and radial directions and connecting it to the leg of another segment coil by welding or the like. The coil 12 is, for example, a three-phase coil and includes three coils 12 for the U-phase, V-phase, and W-phase. The three coils 12 generate a rotating magnetic field in the stator core 11 when a three-phase alternating current is passed through them.

[0013] Figure 2 shows a simplified view of the stator 10 from a direction perpendicular to the axis Ax passing through the center of the stator core 11. The direction of the axis Ax is the axial direction. In Figure 2 and Figure 3 described later, the upward direction D1 and downward direction D2 of the stator 10 are shown. In other words, the stator core 11 is used in a position where the axial direction is oriented horizontally. However, considering the reality that motors including the stator 10 are used, for example, mounted on vehicles, the axial direction does not have to be strictly parallel to the horizontal direction, and may be oriented approximately horizontally, that is, the axial direction may be slightly inclined with respect to the horizontal direction.

[0014] As can be seen from Figures 1 and 2, the coil 12 includes a coil end portion 15 that protrudes outward from the end face 14 of the stator core 11 in the axial direction. Figure 2 shows the coil end portion 15 protruding from one end face 14 in the axial direction and the coil end portion 15 protruding from the other end face 14 in the axial direction. The coil end portion 15 can be considered as the part of the coil 12 that extends outside the slot.

[0015] Figure 2 shows a simplified illustration of some of the refrigerant flow paths 16 by dashed lines. The stator core 11 is provided with multiple refrigerant flow paths 16. Each of the multiple refrigerant flow paths 16 penetrates the stator core 11 along the axial direction and can supply refrigerant to the coil end portions 15 from each opening 16a of the end face 14 of the stator core 11. The refrigerant flow paths 16 only need to extend in the axial direction, and for example, at least a portion of them may be inclined with respect to the axial direction or branched. Furthermore, the multiple refrigerant flow paths 16 are formed at intervals along the circumferential direction.

[0016] Figure 3 shows a simplified view of the end face 14 and coil end portion 15 of the stator core 11 from the axial direction. Figure 3 shows that multiple openings 16a, i.e., multiple refrigerant flow paths 16, are formed at approximately constant intervals along the circumferential direction R on the end face 14. These multiple refrigerant flow paths 16 are formed at approximately constant intervals along the circumferential direction R, surrounding the coil end portion 15 in its vicinity and on its outer side. Refrigerant is supplied to the annular coil end portion 15 almost evenly through the openings 16a of these multiple refrigerant flow paths 16. Needless to say, refrigerant is supplied to the refrigerant flow paths 16 from outside the stator 10 via predetermined flow paths. The method and route of supplying refrigerant to the refrigerant flow paths 16 are not particularly limited in this embodiment. Furthermore, refrigerant is supplied to each coil end portion 15 at each end face 14 on both the axial side and the other side as shown in Figure 2.

[0017] According to this embodiment, the stator 10 includes a plurality of refrigerant guide portions 20 provided at multiple positions on the coil end portion 15. Each of the refrigerant guide portions 20 discharges the refrigerant flowing down the coil end portion 15 to the radial outer circumference of the stator core 11. The refrigerant guide portions 20 are formed of an insulating material.

[0018] FIG. 6 simply shows the conventional stator 1 from the same perspective as in FIG. 3. Regarding the stator 1, the same components as those of the stator 10 according to the present embodiment are denoted by the same reference numerals as in FIG. 3. In FIG. 6, the path along which the refrigerant flows down the surface of the coil end portion 15 is illustrated by the solid arrows. The refrigerant supplied to the coil end portion 15 for cooling flows down along the surface of the coil end portion 15 extending in an annular shape as shown in FIG. 6. The refrigerant is heated by the coil 12 during the flowing-down process and gradually increases in temperature. Therefore, in the lower range of the coil end portion 15 where the heated refrigerant flows down from above, there may be a case where a sufficient cooling effect by the refrigerant cannot be obtained.

[0019] In response to such a problem, in the present embodiment, a refrigerant guide portion 20 is provided. In FIG. 3, the path along which the refrigerant flows down the surface of the coil end portion 15 is illustrated by the solid arrows. The refrigerant heated during the process of flowing down along the annularly extending coil end portion 15 hits the refrigerant guide portion 20 as shown in FIG. 3, is guided by the refrigerant guide portion 20, and is discharged to the radially outer peripheral side of the stator core 11. Therefore, in the range of the coil end portion 15 located below the refrigerant guide portion 20, it is avoided that the refrigerant flowing down while being heated above the refrigerant guide portion 20 is mixed with the newly supplied refrigerant to this range. Accordingly, appropriate cooling by the supplied refrigerant is realized in each of the ranges above and below the refrigerant guide portion 20 of the coil end portion 15, and the cooling effect of the refrigerant on the coil end portion 15 can be improved as compared with the conventional case.

[0020] The characteristics of the refrigerant guide portion 20 will be further described. The position and number of the refrigerant guide portions 20 provided in the coil end portion 15 vary. The plurality of refrigerant guide portions 20 may be provided, for example, at regular angular intervals along the circumferential direction. Also, the plurality of refrigerant guide portions 20 may be provided, for example, symmetrically with respect to the position of the axis Ax of the stator core 11. In the example of FIG. 3, two refrigerant guide portions 20 are provided at symmetric positions with respect to the position of the axis Ax of the stator core 11.

[0021] In view of suppressing the temperature non-uniformity of the annular coil end portion 15 and cooling it as uniformly as possible, providing a plurality of refrigerant guide portions 20 at regular angular intervals along the circumferential direction or providing them symmetrically with respect to the position of the axis core Ax can be said to be one of the preferred embodiments. In addition to the example shown in FIG. 3, for example, four refrigerant guide portions 20 may be provided at intervals of 90 degrees along the circumferential direction and at symmetric positions with respect to the position of the axis core Ax.

[0022] In FIG. 3, a horizontal center boundary line C passing through the position of the axis core Ax is shown by a dashed line. As an example, the refrigerant guide portion 20 may be provided at a position where the center boundary line C passes or at a position below the center boundary line C. In the example of FIG. 3, two refrigerant guide portions 20 are provided at the position where the center boundary line C passes. That is, when the top position of the annular coil end portion 15 is set to 0 degrees, the refrigerant guide portions 20 are provided at positions at 90 degrees and 270 degrees in the clockwise angle.

[0023] When the refrigerant guide portion 20 is provided at a position above the center boundary line C in the coil end portion 15, it becomes relatively difficult to form the refrigerant guide portion 20 so that the refrigerant is discharged to the radially outer peripheral side of the stator core 11. On the other hand, by providing the refrigerant guide portion 20 at a position where the center boundary line C passes or at a position below the center boundary line C, it becomes easier to discharge the refrigerant to the radially outer peripheral side of the stator core 11. Further, since the refrigerant guide portion 20 covers a part of the surface of the coil end portion 15, from the viewpoint of ensuring a large contact area between the refrigerant and the coil end portion 15, it is preferable that the area covered by the refrigerant guide portion 20 is small. Therefore, as shown in FIG. 3, the embodiment in which two refrigerant guide portions 20 are provided at the position where the center boundary line C passes can be said to be one of the ideal embodiments for the purpose of enhancing the cooling effect by the refrigerant while discharging the heated refrigerant.

[0024] In addition, for example, in addition to the two refrigerant guide portions 20 shown in FIG. 3, it is also possible to provide a plurality of refrigerant guide portions 20 at a position below the center boundary line C.

[0025] Figure 4 is a perspective view from the radial outer periphery of the refrigerant guide section 20 and a portion of the coil end section 15 before it is attached to a portion of the coil end section 15. Figure 5 is a perspective view from the radial outer periphery of the state in which the refrigerant guide section 20 has been attached to a portion of the coil end section 15. As shown in Figure 4, the refrigerant guide section 20 is composed of three wall sections 21, 22, and 23. The wall sections 21 and 23 are substantially parallel to each other and spaced apart in the radial direction. Wall section 22 is substantially perpendicular to the wall sections 21 and 23 and extends radially, connecting wall sections 21 and 23.

[0026] When such a refrigerant guide portion 20 is attached to the coil end portion 15, the wall portion 21 becomes an inner circumferential wall portion 21 that covers the radially inner side surface of the coil end portion 15. Also, when the refrigerant guide portion 20 is attached to the coil end portion 15, the wall portion 23 becomes an outer circumferential wall portion 23 that covers the radially outer side surface of the coil end portion 15, and the wall portion 22 becomes a connecting wall portion 22 that covers the axially facing end face of the coil end portion 15 and connects the inner circumferential wall portion 21 and the outer circumferential wall portion 23. Thus, the refrigerant guide portion 20 comprises an inner circumferential wall portion 21, an outer circumferential wall portion 23, and a connecting wall portion 22.

[0027] The method for providing the refrigerant guide portion 20 to the coil end portion 15 is not particularly limited. For example, as shown in Figure 4, a pre-formed refrigerant guide portion 20 can be attached to a part of the coil end portion 15 via an adhesive or the like. Alternatively, a refrigerant guide portion 20 can be provided to a part of the coil end portion 15 by molding resin, as shown in Figure 5.

[0028] As can be seen from Figures 4 and 5, the inner circumferential side wall portion 21, the connecting wall portion 22, and the outer circumferential side wall portion 23 of the refrigerant guide portion 20 each have a predetermined thickness. Therefore, this thickness ensures the upper surface 24 (see Figure 3) of the refrigerant guide portion 20. The upper surface 24 is the surface facing upward D1. The upper surface 24 receives the refrigerant that flows down from above along the surface of the coil end portion 15.

[0029] The upper surface 24 of the refrigerant guide portion 20 may be inclined downward toward the radial outer circumference. As shown in Figure 3, the upper surfaces 24 of each of the two refrigerant guide portions 20 are inclined downward toward the radial outer circumference. By inclining the upper surface 24 in this way, the refrigerant guide portion 20 can receive the refrigerant flowing down along the coil end portion 15 with its upper surface 24 and reliably discharge it toward the radial outer circumference of the stator core 11.

[0030] In the coil end portion 15, the portion to which the refrigerant guide portion 20 is attached may be filled with resin, for example, in the gaps between the multiple segment coils that make up the coil 12 and the gap with the refrigerant guide portion 20. In this way, it is possible to reliably prevent the refrigerant flowing down the coil end portion 15 above the refrigerant guide portion 20 from flowing into the coil end portion 15 below the refrigerant guide portion 20.

[0031] The upper surface 24 may, for example, have a protruding edge that projects upward from the end away from the coil end portion 15. With such a configuration, the upper surface 24 can collect and discharge a certain amount of refrigerant flowing down the upper coil end portion 15. In other words, the upper surface 24 may be processed into a gutter-like shape.

[0032] The specific examples of the technologies disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples described above. Furthermore, the technical elements described herein or in the drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated herein or in the drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of symbols]

[0033] 10: Stator, 11: Stator core, 12: Coil, 13: Teeth section, 14: End face, 15: Coil end section, 16: Refrigerant flow path, 16a: Opening, 20: Refrigerant guide section, 21: Inner circumferential side wall section, 22: Connecting wall section, 23: Outer circumferential side wall section, 24: Top surface

Claims

1. A stator in which the coil is cooled by a refrigerant, Multiple teeth are projected radially toward the inner circumference, and the stator core is cylindrical with its axial direction horizontal or substantially horizontal. A coil wound around the plurality of teeth and extending along the circumferential direction of the stator core, the coil including a coil end portion that protrudes outward from the end face of the stator core in the axial direction, Each of the refrigerant flows penetrates the stator core along the axial direction and is capable of supplying the refrigerant to the coil end portion from each opening on the end face of the stator core, and is formed at intervals along the circumferential direction, A stator comprising: a plurality of refrigerant guide portions provided at multiple positions of the coil end portion, which discharge the refrigerant flowing down the coil end portion toward the radial outer circumference of the stator core.

2. The stator according to claim 1, wherein the plurality of refrigerant guide portions are provided at positions through which a horizontal central boundary line passing through the axial position of the stator core passes, or at positions below the central boundary line.

3. The stator according to claim 1, wherein the plurality of refrigerant guide sections are provided symmetrically on both sides of the axial position of the stator core.

4. The stator according to claim 1, wherein the refrigerant guide portion comprises an inner circumferential wall portion that covers the radially inner side surface of the coil end portion, an outer circumferential wall portion that covers the radially outer side surface of the coil end portion, and a connecting wall portion that covers the axially facing end surface of the coil end portion and connects the inner circumferential wall portion and the outer circumferential wall portion.

5. The stator according to claim 1, wherein the refrigerant guide portion has an upper surface for receiving the refrigerant, and the upper surface is inclined downward toward the radial outer circumference.

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