Rotor structure

Abstract

To provide a rotor structure capable of efficiently cooling a cooling target part inside a synchronous motor.SOLUTION: A rotor structure that supplies oil to a cooling target part inside a synchronous motor in which a rotor 10 rotates synchronizing with a revolving magnetic field generated in a stator is provided. The rotor 10 includes a plurality of permanent magnets 101, 102, 103, and 106, which is one cooling target part, and a cylindrical rotor core 30 in which a plurality of magnet holes 31 for having the permanent magnets 101 and 102 embedded therein are formed. The rotor 10 is configured so that the oil flows in an axial direction inside the rotor core 30, passing through the plurality of magnet holes 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a rotor structure, and more particularly to a rotor structure for supplying oil to a part to be cooled inside a synchronous motor. [Background technology]

[0002] As electric vehicles become more widespread, there is a demand for improvements in the mountability and productivity of the motors that drive them, as well as for easier deployment in a wider range of vehicle models and lower costs. To achieve these goals, it is necessary to reduce the size of the motor while maintaining its output, in other words, to increase the output density of the motor.

[0003] Increasing the output density of a motor unavoidably requires increasing the density of the current flowing through the stator coil. However, increasing the current density in a synchronous motor increases the amount of heat generated by the permanent magnets, causing the temperature of various parts inside the motor to rise. In some cases, this may lead to demagnetization of the permanent magnets and ultimately a decrease in motor torque.

[0004] Therefore, in order to cool the permanent magnets inside the rotor core, for example, Patent Document 1 discloses a rotor for a rotating electric machine that is provided with a coolant flow path that extends in the axial direction near the magnets housed in the rotor core. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-176235 Summary of the Invention [Problem to be solved by the invention]

[0006] In a motor, the rotor core itself generates heat, and in a configuration in which the cooling target (permanent magnet) is cooled by a refrigerant (cooling oil) supplied to a refrigerant flow path provided near the cooling target, as in Patent Document 1, the cooling oil may heat up due to heat exchange with the rotor core before the cooling target is cooled, which may result in insufficient cooling of the cooling target. Therefore, Patent Document 1 leaves room for improvement in terms of efficient cooling of the cooling target inside the motor.

[0007] The present invention has been made in view of the above points, and an object of the present invention is to provide a rotor structure that can efficiently cool the parts to be cooled inside a synchronous motor. [Means for solving the problem]

[0008] To achieve the above object, in the rotor structure according to the present invention, the permanent magnets embedded in the rotor are directly cooled by oil.

[0009] Specifically, the present invention is directed to a rotor structure that supplies oil to parts to be cooled inside a synchronous motor in which the rotor rotates in synchronization with a rotating magnetic field generated by the stator.

[0010] This rotor structure is characterized in that the rotor comprises a plurality of permanent magnets, which are one of the cooling targets, and a cylindrical rotor core in which each of the permanent magnets is embedded and in which a plurality of axially extending magnet holes are formed, and is configured so that oil flows axially inside the rotor core through the magnet holes.

[0011] With this configuration, oil flows axially inside the rotor core through the magnet holes in which the permanent magnets are embedded, allowing the oil to directly cool the permanent magnets, which are one of the parts to be cooled. This allows the permanent magnets, which are one of the parts to be cooled, to be cooled more efficiently than, for example, a structure in which oil flows through holes (oil passages) provided near the permanent magnets in the rotor core.

[0012] However, if the oil passages in the rotor shaft are directly connected to the magnet holes, the amount of oil supplied to the magnet holes may vary. If the amount of oil varies, some of the permanent magnets embedded in the rotor core may not be sufficiently cooled, causing some of the permanent magnets to be demagnetized and resulting in a decrease in torque.

[0013] Therefore, in the above rotor structure, the rotor further comprises a rotor shaft that is inserted into the rotor core so that it cannot rotate relative to the rotor core, and a circular one-side end plate that is attached to one axial end of the rotor core concentrically with the axis of the rotor core, and the one-side end plate has a chamber space that is circular when viewed axially and concentrically with the axis of the rotor core, and the one-side end plate may be configured so that oil is filled into the chamber space from an oil passage in the rotor shaft and the oil is distributed from the chamber space to the multiple magnet holes.

[0014] With this configuration, instead of sending oil directly from the oil passage in the rotor shaft to the magnet holes, oil is first filled into a chamber space formed in one end plate, and then the oil is distributed from the annular chamber space to multiple magnet holes, allowing oil to be supplied evenly to multiple magnet holes formed in the rotor core.

[0015] Furthermore, the oil distributed to the magnet holes is only filled into the chamber space once, and is supplied to the magnet holes in a sufficiently cooled state, rather than after cooling (heating) the rotor core, etc., so the permanent magnets can be cooled effectively.

[0016] As a result, it is possible to prevent some of the permanent magnets from being cooled insufficiently, and therefore it is possible to reliably prevent the permanent magnets from being demagnetized, and ultimately to prevent a decrease in torque.

[0017] Furthermore, in the rotor structure, the one-side end plate is provided with a plurality of radial oil passages extending radially on the other axial side of the chamber space, with radially inner ends communicating with the chamber space and radially outer ends communicating with the plurality of magnet holes, and each of the radial oil passages may be connected in an R-shape when viewed circumferentially, with a surface defining the radial oil passage on one axial side and a surface defining the radial oil passage on the radially outer side.

[0018] According to this configuration, multiple radial oil passages are formed, extending radially on the other axial side (closer to the rotor core) of the chamber space, with their radially inner ends communicating with the chamber space and their radially outer ends communicating with multiple magnet holes.Therefore, the oil filled in the chamber space can be evenly distributed to the multiple magnet holes through these multiple radial oil passages.

[0019] Here, while oil flows radially outward through the radial oil passages, it flows axially when supplied to the magnet holes. If the surface that defines the radial oil passages on one axial side (referred to as the "first partition screen") and the surface that defines the radial oil passages on the radially outer side (referred to as the "second partition screen") are perpendicular to each other, it is possible that the oil will not change direction smoothly. In addition, when the motor is running, which increases the need for cooling, the rotor is constantly rotating and centrifugal force acts on the oil, so the oil that flows radially through the radial oil passages is likely to be pressed against the second partition screen. Therefore, in a structure where the first partition screen and the second partition screen are perpendicular to each other, it is possible that the oil will have even more difficulty changing direction.

[0020] In this regard, in this configuration, the first section screen and the second section screen are connected in an R-shape when viewed circumferentially, so that under centrifugal force, when the oil that flows radially outward through the radial oil passage is supplied to the magnet hole, it can smoothly change direction in the axial direction, thereby more efficiently cooling the permanent magnet, which is the part to be cooled.

[0021] Furthermore, in the rotor structure, the one-side end plate has a plurality of radial oil passages formed therein, which extend radially on the other axial side of the chamber space, and whose radially inner ends communicate with the chamber space and whose radially outer ends communicate with the plurality of magnet holes, and the radially outer ends of each of the radial oil passages may be connected to the radially inner portions of each of the magnet holes.

[0022] As mentioned above, when the motor is running and cooling is required more, the rotor is constantly rotating and centrifugal force acts on the oil, so the oil flowing axially through the magnet bore also tends to collect in the radially outer part of the magnet bore. For this reason, if the radially outer end of the radial oil passage were connected to the radially outer part of the magnet bore where oil collects, it is possible that the oil would not be able to be smoothly introduced into the magnet bore.

[0023] In this regard, with this configuration, the radially outer end of the radial oil passage is connected to the radially inner portion of each magnet hole, in other words, it is connected to the portion of the magnet hole where oil is less likely to collect, so oil can be smoothly introduced from the radial oil passage into the magnet hole, thereby more efficiently cooling the permanent magnets, which are the parts to be cooled.

[0024] Furthermore, in the rotor structure, the one-side end plate is arranged so as to overlap radially with the coil end on one axial side, which is one of the cooling targets, of the stator coil attached to the stator, and the one-side end plate is formed with a plurality of first diffusion oil passages extending radially on one axial side of the chamber space, with their radially inner ends communicating with the chamber space and opening on the outer peripheral surface of the one-side end plate, and each of the first diffusion oil passages may be formed so that its cross-sectional area increases radially outward.

[0025] With this configuration, a plurality of first diffusion oil passages are formed, extending radially on one axial side of the chamber space (the opposite side of the rotor core across the chamber space), with their radially inner ends communicating with the chamber space and opening on the outer peripheral surface of the one-side end plate, so that some of the oil filled in the chamber space can be scattered radially outward from the outer peripheral surface of the one-side end plate by centrifugal force through the plurality of first diffusion oil passages. Thus, the one-side end plate in which the first diffusion oil passages are formed is positioned so as to overlap the coil end on one axial side when viewed radially, so that the coil end on one axial side, which is one of the parts to be cooled, can be cooled.

[0026] Furthermore, the oil that is blown to the coil ends is simply filled into the chamber space once, just like the oil distributed to the magnet holes, and is supplied to the coil ends in a sufficiently cooled state, rather than after cooling (heating) the rotor core, etc., so not only the permanent magnets but also the coil ends can be cooled efficiently.

[0027] If the first diffusion oil passage were to become clogged with oil, negative pressure would be generated within the passage, which would impair the uniformity of the oil within the chamber space and potentially prevent the oil from being evenly distributed to the multiple magnet holes. In this regard, with this configuration, the first diffusion oil passage is formed so that its cross-sectional area increases as it moves radially outward, which prevents the first diffusion oil passage from becoming clogged with oil, making it possible to cool the coil ends while maintaining efficient cooling of the permanent magnets.

[0028] Furthermore, in the rotor structure, the rotor further has an annular other-side end plate attached concentrically to the axis of the rotor core at the other axial end of the rotor core, and the other-side end plate is arranged so as to overlap radially with the other axial side coil end, which is one of the cooling targets in the stator coil, and the other-side end plate is formed with a plurality of second diffusion oil passages that extend radially, have radially inner ends that communicate with the plurality of magnet holes, open at the outer peripheral surface of the other-side end plate, and have a cross-sectional area that increases radially outward, and the number of the second diffusion oil passages may be set to be greater than the number of the first diffusion oil passages.

[0029] With this configuration, as with the first diffusion oil passage described above, it is possible to cool the coil end on the other axial side, which is one of the parts to be cooled. Also, like the first diffusion oil passage, the second diffusion oil passage is formed so that its cross-sectional area increases radially outward, which prevents the second diffusion oil passage from becoming clogged with oil. This prevents, for example, the amount of oil flowing through the magnet hole communicating with the second diffusion oil passage where negative pressure is generated from increasing, thereby preventing the even distribution of oil from being impaired.

[0030] Unlike the coil ends on one side of the axial direction, the coil ends on the other side of the axial direction are supplied with oil (that has been heated to a certain extent) after cooling the rotor core, etc. However, since the number of second diffusion oil passages is set to be greater than the number of first diffusion oil passages (the amount of oil supplied to the coil ends on the other side of the axial direction is relatively greater), the coil ends on the other side of the axial direction can also be cooled efficiently.

[0031] In the rotor structure, the rotor core may have a skew angle of 0 degrees.

[0032] According to this configuration, by making the rotor core so-called skewless, the flow resistance of the oil flowing through the magnet holes can be reduced, thereby enabling the permanent magnets, which are the parts to be cooled, to be cooled more efficiently. [Effects of the Invention]

[0033] As described above, the rotor structure according to the present invention can efficiently cool the parts to be cooled inside the synchronous motor. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a longitudinal sectional view schematically illustrating an outline of a synchronous motor according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram illustrating an example of a cooling system in an electric vehicle. [Figure 3] FIG. 2 is a perspective view schematically showing a space in the rotor through which oil flows. [Figure 4] FIG. 2 is a perspective view illustrating the direction of oil flow in the rotor. [Figure 5] FIG. 2 is a diagram schematically illustrating an oil introduction portion. [Figure 6] FIG. 2 is a diagram schematically illustrating a main part of a shaft main body. [Figure 7] FIG. 2 is a diagram schematically illustrating a rotor shaft. [Figure 8] FIG. 2 is a cross-sectional view schematically showing a rotor core and a permanent magnet. [Figure 9] FIG. 4 is a diagram schematically illustrating a second end plate. [Figure 10] FIG. 10 is a diagram schematically illustrating a third end plate. [Figure 11] FIG. 10 is a diagram schematically illustrating a state in which the second end plate and the third end plate are stacked. [Figure 12] FIG. 3 is a diagram schematically illustrating a state in which the first end plate and the second end plate are stacked. [Figure 13] FIG. 10 is a diagram schematically showing a state in which a third end plate is attached to a rotor core. [Figure 14] FIG. 2 is a cross-sectional view schematically showing a main part of a rotor core. [Figure 15] FIG. 4 is a perspective view schematically showing a radial oil passage. [Figure 16] FIG. 10 is a diagram schematically illustrating a fourth end plate. [Figure 17] FIG. 10 is a diagram schematically illustrating a fifth end plate. [Figure 18] FIG. 10 is a diagram schematically illustrating a state in which the fourth end plate and the fifth end plate are stacked. [Figure 19] FIG. 2 is a perspective view schematically showing outer and inner through holes. [Figure 20] FIG. 10 is a diagram schematically illustrating an example of an oil passage according to another embodiment. [Figure 21] FIG. 10 is a perspective view schematically showing a rotor core according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0036] -Motor Overview- Fig. 1 is a longitudinal cross-sectional view that schematically illustrates a synchronous motor 1 according to this embodiment. In Fig. 1, the symbol AC indicates the axis of the synchronous motor 1, the symbol OS indicates the output shaft side (the other axial side), and the symbol AOS indicates the anti-output shaft side (one axial side). In addition, for the sake of clarity, Fig. 1 does not show a detailed cross section of a stator core 91 of a stator 90, but only shows the outer shape of the stator core 91 and coil ends 93a, 93b of a stator coil 93 that is attached to the stator core 91.

[0037] The synchronous motor 1 according to this embodiment is mounted, for example, on an electric vehicle, and as shown in FIG. 1, comprises a rotor 10 having a rotor core 30 with a rotor shaft 20 passing through the center, and a stator 90 having a stator core 91 arranged to surround the outer periphery of the rotor core 30, and is configured so that the rotor 10 rotates in synchronization with the rotating magnetic field generated by the stator 90.

[0038] The rotor shaft 20 has an oil introduction portion 21 and a shaft main body 27, and an oil introduction passage 20a through which oil flows is formed inside. In addition to the rotor shaft 20 and the rotor core 30, the rotor 10 also has permanent magnets 101, 102, 103, and 106 (see FIG. 3, etc.) embedded in magnet holes 31 (see FIG. 8) formed in the rotor core 30, and first to fifth end plates 40, 50, 60, 70, and 80 attached to the ends of the rotor core 30 in the axial direction (the direction in which the axis AC extends). Note that FIG. 1 merely shows a schematic diagram of the synchronous motor 1, and since emphasis is placed on ease of understanding, the circumferential positions of the components of the rotor 10 are not necessarily aligned.

[0039] -Cooling System- Fig. 2 is a block diagram illustrating an example of a cooling system 2 in an electric vehicle. As shown in Fig. 2, this cooling system 2 includes an inverter cooling system 3 and a motor cooling system 4, and a heat exchanger 8 is interposed between the inverter cooling system 3 and the motor cooling system 4.

[0040] The inverter cooling system 3 has a circulation path 3a through which the coolant circulates, and an inverter 5, a radiator 6, and a water pump 7 that circulates the coolant, each of which is provided on the circulation path 3a. In this inverter cooling system 3, heat generated by the inverter 5 is absorbed by the coolant, and the heat absorbed by the coolant is dissipated to the outside by the radiator 6, thereby maintaining the coolant and the inverter 5 at low temperatures.

[0041] Meanwhile, the motor cooling system 4 has a circulation path 4a through which oil circulates, and the motor 1 and oil pump 9 that pumps oil to the oil inlet 21 of the rotor shaft 20, both of which are provided on the circulation path 4a. In this motor cooling system 4, the heat generated in the synchronous motor 1 is absorbed by the oil, and the oil that has absorbed the heat collects at the bottom of the motor housing (not shown) and then returns to the circulation path 4a. In this motor cooling system 4, the heat absorbed by the oil is absorbed by the coolant through indirect heat exchange between the circulation paths 3a and 4a in the heat exchanger 8, and then the heat is radiated to the outside by the radiator 6, thereby maintaining the oil at a relatively low temperature.

[0042] In this embodiment, the cooling system 2 configured as described above allows oil maintained at a relatively low temperature (for convenience, also referred to as "fresh oil") to be sent to the oil introduction section 21 of the rotor shaft 20.

[0043] -Outline of rotor structure- Fig. 3 is a perspective view schematically showing the space through which oil flows in the rotor 10, and Fig. 4 is a perspective view schematically explaining the direction of oil flow in the rotor 10. In the rotor structure employed in this embodiment, fresh oil sent to the oil inlet 21 of the rotor shaft 20 as described above is appropriately distributed at the second and third end plates 50, 60 and is supplied directly to the gaps 31a in the magnet holes 31 in which the permanent magnets 101, 102, ..., which are one of the parts to be cooled inside the synchronous motor 1, are embedded, as shown by the thick arrows in Fig. 1, thereby efficiently cooling the permanent magnets 101, 102, ....

[0044] Similarly, fresh oil is supplied directly to the coil end 93a of the AOS on the opposite axial side to the output shaft (hereinafter simply referred to as the "opposite output shaft AOS"), which is one of the parts to be cooled, so that the coil end 93a is efficiently cooled. Furthermore, in this rotor structure, the oil that has cooled the permanent magnets 101, 102, ... is also used to efficiently cool the coil end 93b of the OS on the opposite axial side to the output shaft (hereinafter simply referred to as the "output shaft OS"), which is one of the parts to be cooled.

[0045] More specifically, in the rotor structure of this embodiment, a space S through which oil flows is formed inside the rotor shaft 20, the rotor core 30, and the first to fifth end plates 40, 50, ..., as shown by hatching in Fig. 3. As a result, in this rotor structure, as shown by the thick arrows in Fig. 4, oil flows circumferentially, radially, and axially, in other words, three-dimensionally, inside the rotor shaft 20, the rotor core 30, and the first to fifth end plates 40, 50, ..., and is supplied to the target cooling target.

[0046] The rotor structure that allows such a three-dimensional oil flow will be described in detail below.

[0047] -Details of rotor structure- <Rotor shaft> The rotor shaft 20 is inserted into the central hole 38 (see FIG. 8) of the cylindrical rotor core 30 so as not to rotate relative to the motor housing, and is rotatably supported by the motor housing, thereby enabling the rotor core 30 to rotate relative to the motor housing and also serving to introduce fresh oil from the AOS on the anti-output shaft side of the rotor 10 through the oil introduction passage 20a. As described above, the rotor shaft 20 has the oil introduction portion 21 and the shaft main body portion 27.

[0048] <Oil inlet> FIG. 5 is a diagram schematically illustrating the oil introduction portion 21. FIG. 5(a) is a perspective view of the oil introduction portion 21. FIG. 5(b) is a diagram illustrating the surface of the oil introduction portion 21 on the output shaft side OS. FIG. 5(c) is a cross-sectional view taken along line cc in FIG. 5(a). As shown in FIG. 5(a), the oil introduction portion 21 is formed in a shape in which a cylindrical small diameter portion 22 and a cylindrical large diameter portion 23 having an outer diameter larger than that of the small diameter portion 22 are connected in the axial direction via a stepped surface so that they are concentric about the axis AC.

[0049] The oil introduction portion 21 is formed with an oil introduction hole 24 that passes through the small-diameter portion 22 and the large-diameter portion 23 in the axial direction, passing through their respective axial centers. Furthermore, as shown in FIGS. 5( a) to 5(c), an end of the output-shaft-side OS of the large-diameter portion 23 is formed with a recess 25 that has a circular cross section and is recessed into the non-output-shaft-side AOS. The recess 25 communicates with the oil introduction hole 24 at its center. Furthermore, as shown in FIGS. 5(a) and 5(b), eight oil discharge grooves 26 are formed at the end of the output-shaft-side OS of the large-diameter portion 23, extending radially outward from the recess 25 at equal 45-degree intervals in the circumferential direction and recessed into the non-output-shaft-side AOS. The radially inner end of each oil discharge groove 26 communicates with the recess 25, and the radially outer end opens at the outer peripheral surface of the large-diameter portion 23.

[0050] <Shaft body> FIG. 6 is a diagram schematically showing a main portion of the shaft main body 27. FIG. 6(a) is a perspective view of the main portion of the shaft main body 27. FIG. 6(b) is a cross-sectional view taken along line bb in FIG. 6(a). FIG. 6(c) is a cross-sectional view taken along line cc in FIG. 6(a). As shown in FIG. 6(a), the shaft main body 27 is formed in a cylindrical shape centered on the axis AC, and its inner diameter is set to be slightly larger than the outer diameter of the large diameter portion 23.

[0051] As shown in Figures 6(a) and 6(c), the shaft main body 27 is provided with a disk-shaped partition plate 28 that divides the hollow portion in the axial direction. The length from the end of the anti-output-shaft-side AOS of the shaft main body 27 to the surface of the anti-output-shaft-side AOS of the partition plate 28 is set to the same length in the axial direction as the large-diameter portion 23. Furthermore, as shown in Figures 6(a) and 6(b), the shaft main body 27 is formed with eight oil discharge holes 29 that extend radially outward in the radial direction at equal 45-degree intervals around the circumferential direction and penetrate the shaft main body 27. The oil discharge holes 29 are circular holes with a diameter approximately the same as the depth of the oil discharge groove 26, and are formed in positions that contact the surface of the anti-output-shaft-side AOS of the partition plate 28.

[0052] <Oil inlet path> FIG. 7 is a schematic diagram of the rotor shaft 20. FIG. 7(a) is a perspective view of a main portion of the shaft main body 27. FIG. 7(b) is a cross-sectional view taken along line bb in FIG. 7(a). FIG. 7(c) is a cross-sectional view taken along line cc in FIG. 7(a). FIG. 7(d) is a perspective view showing the flow of oil inside the rotor shaft 20. The rotor shaft 20 is a combination of the oil introduction portion 21 and the shaft main body 27 configured as described above. Specifically, the rotor shaft 20 is configured by fitting the large diameter portion 23 into the hollow portion of the shaft main body 27 so that the circumferential positions of the eight oil discharge grooves 26 and the eight oil discharge holes 29 coincide with each other, and then joining the two by welding or the like.

[0053] When the oil inlet portion 21 and the shaft main body portion 27 are combined, the recessed portion 25 and the oil discharge groove 26 are covered by the surface of the partition plate 28 on the side AOS opposite the output shaft, thereby forming a disk-shaped space 25' and an oil discharge path 26' with a closed cross section. As a result, fresh oil flows through the oil inlet hole 24 to the output shaft side OS, fills the disk-shaped space 25', flows from this disk-shaped space 25' through the oil discharge path 26' radially outward, and is then sent radially outward to the outside of the rotor shaft 20 through the oil discharge holes 29, forming an oil inlet path 20a.

[0054] In this manner, the oil flow shown in FIG. 7(d), in other words, the part of the oil flow in the rotor 10 shown in FIG. 4 that corresponds to the rotor shaft 20, is realized.

[0055] <Rotor core> FIG. 8 is a cross-sectional view schematically showing the rotor core 30 and permanent magnets 101, 102, .... FIG. 8(a) is an overall view of the rotor core 30. FIG. 8(b) is an enlarged view of the magnetic poles separated by the dashed lines in FIG. 8(a). The rotor core 30 is a laminate formed by axially stacking a predetermined number of annular magnetic thin plates formed into a predetermined shape, and as shown in FIG. 8(a), it is formed into a cylindrical shape having a central hole 38 to which the rotor shaft 20 is fixed by shrink fitting. Note that the magnetic thin plates can be made of electromagnetic steel plates, which are a type of silicon steel plate.

[0056] The rotor core 30 is formed with a plurality of axially extending magnet holes 31, 33, 34, 35, 36 so that the rotor 10 has eight magnetic poles and the angle of view φ of one magnetic pole along the circumferential direction as seen from the axis AC is 45 degrees, and permanent magnets 101, 102, 103, 104, 105, 106 are embedded in these magnet holes 31, 33, .... The rotor core 30 is configured so that the skew angle is 0 degrees, and therefore the magnet holes 31, 33, ... and permanent magnets 101, 102, ... extend straight in the axial direction from the end of the rotor core 30 on the anti-output shaft side AOS to the end of the rotor core 30 on the output shaft side OS. Although the positions and shapes of the magnet holes 31, 33, ... and permanent magnets 101, 102, ... of each magnetic pole are different, the basic configuration is the same. Therefore, we will explain the magnet holes 31, 33, ... and permanent magnets 101, 102, ... of each magnetic pole by referring to the magnetic pole shown in the enlarged view of Figure 8(b) as a representative of the eight magnetic poles.

[0057] As shown in Fig. 8(b), each magnetic pole has a two-layer structure consisting of an outer embedded magnet section 100A including two permanent magnets 101, 102 arranged in a V-shape on the radially outer side, and an inner embedded magnet section 100B including four permanent magnets 103, 104, 105, 106 arranged in a U-shape on the radially inner side. Note that the protrusions 37 and the gaps 37a within the protrusions 37 shown in Fig. 8 are intended to suppress the generation of harmonic components contained in the magnetic flux, and are not relevant to this embodiment, so detailed description thereof will be omitted.

[0058] The outer embedded magnet portion 100A has one magnet hole 31, and the two permanent magnets 101, 102 are inserted into the magnet hole 31 so as to form a V-shape, with the distance between them increasing radially outward and decreasing radially inward. Portions of the magnet hole 31 that are not filled with the two permanent magnets 101, 102 and portions partitioned by bridges 39 remain as gaps (flux barriers) 31a, 31b, 31c, 31d, and 31e. Of these gaps 31a, 31b, 31c, 31d, and 31e, gap 31c serves as an oil path through which oil flows to cool the permanent magnets 101, 102, as will be described later.

[0059] The inner embedded magnet portion 100B has four magnet holes 33, 34, 35, and 36. The permanent magnets 103 and 106 are inserted into the magnet holes 33 and 36, respectively, so that the spacing between them increases radially outward and decreases radially inward. The portions of the magnet holes 33 and 36 that are not filled with the permanent magnets 103 and 106 remain as gaps 33a, 33b, 36a, and 36b. The permanent magnets 104 and 105 are inserted into the magnet holes 34 and 35, respectively, and the portions of the magnet holes 34 and 35 that are not filled with the permanent magnets 104 and 105 remain as gaps 34a and 35a. Of these gaps 33a, 33b, 34a, 35a, 36a, and 36b, the gaps 33b and 36a serve as oil paths through which oil for cooling the permanent magnets 103 and 106 flows, as will be described later.

[0060] <End plate on the opposite side of the output shaft> 1, 3, and 4, the end plates attached to the end of the AOS on the anti-output shaft side of rotor core 30 include first to third end plates 40, 50, and 60. In relation to the claims, the first to third end plates 40, 50, and 60 of this embodiment correspond to what is referred to in the present invention as "annular one-side end plates attached to one axial end of the rotor core, concentrically with the axis of the rotor core."

[0061] The first to third end plates 40, 50, and 60 are annular aluminum plates having outer shapes that are the same as the outer and inner peripheral surfaces of the rotor core 30, respectively, and are assembled by welding or the like to form the end plates of the non-output-shaft-side AOS. As shown in FIG. 1, the first to third end plates 40, 50, and 60 are arranged so as to overlap radially with the coil end 93a of the non-output-shaft-side AOS, which is one of the parts to be cooled. As shown in FIG. 12(a) below, the first end plate 40 has both a flat front surface 40a (the surface of the non-output-shaft-side AOS) and a flat back surface 40b (the surface of the output-shaft-side OS), and is therefore not particularly distinctive, and therefore a detailed description thereof will be omitted.

[0062] <Second end plate> FIG. 9 is a schematic diagram of the second end plate 50. FIG. 9(a) is a diagram showing the surface (front surface 50a) of the AOS on the side opposite the output shaft. FIG. 9(b) is a cross-sectional view taken along line bb in FIGS. 9(a) and 9(c). FIG. 9(c) is a diagram showing the surface (back surface 50b) of the OS on the output shaft side. FIG. 9(d) is a perspective view showing the first diffusion groove 51. FIG. 9(e) is a perspective view showing the annular groove 53 and the connecting groove 55. The figures enclosed in bold frames in FIGS. 9(a) and 9(c) are partially enlarged views of the area enclosed by the dashed lines. In FIG. 9(b), the thickness of the second end plate 50 is exaggerated compared to its diameter for clarity.

[0063] 9(a) and 9(d), eight first diffusion grooves 51 are formed on the surface 50a of the second end plate 50. The first diffusion grooves 51 extend radially outward at equal 45-degree intervals around the circumferential direction and are recessed toward the output shaft side OS. Each first diffusion groove 51 extends to the outer peripheral surface 50c of the second end plate 50 and opens at the outer peripheral surface 50c, and the groove width increases radially outward.

[0064] 9(c) and 9(e), an annular groove 53 having a circular ring shape is formed on the back surface 50b of the second end plate 50, recessed into the anti-output-shaft AOS, and is concentric with the axis AC of the second end plate 50. In addition, eight connecting grooves 55 are formed on the back surface 50b of the second end plate 50. The connecting grooves 55 extend radially outward from the inner circumferential surface of the second end plate 50 at equal 45-degree intervals around the circumferential direction and connect to the annular groove 53. The connecting grooves 55 are recessed into the anti-output-shaft AOS.

[0065] As shown within the bold frames in Figures 9(a) and 9(c) and in Figure 9(b), the radially inner ends of the first diffusion grooves 51 formed on the front surface 50a overlap with the annular groove 53 formed on the back surface 50b when viewed in the axial direction. The eight first diffusion grooves 51 formed on the front surface 50a and the eight connecting grooves 55 formed on the back surface 50b are aligned in the circumferential direction and extend radially on the same radius. Furthermore, the first diffusion grooves 51 formed on the front surface 50a and the annular groove 53 formed on the back surface 50b are connected to each other through a connecting hole 57 with a circular cross section that extends in the axial direction at the overlapping portion.

[0066] <Third end plate> FIG. 10 is a schematic diagram of the third end plate 60. FIG. 10(a) is a diagram showing the surface (front surface 60a) of the AOS on the counter-output shaft side. FIG. 10(b) is a cross-sectional view taken along line bb in FIGS. 10(a) and 10(c). FIG. 10(c) is a diagram showing the surface (back surface 60b) of the OS on the output shaft side. FIG. 10(d) is a perspective view showing the annular groove 63 and the connecting groove 65. FIG. 10(e) is a perspective view showing the first and second radial grooves 61, 62. The figures enclosed in bold frames in FIGS. 10(a) and 10(c) are partially enlarged views of the dashed frame. In FIG. 10(b), the thickness of the third end plate 60 is exaggerated compared to its diameter for clarity.

[0067] 10(c) and 10(e), an annular groove 63 having a circular ring shape is formed in the surface 60a of the third end plate 60, recessed toward the output shaft side OS, and is concentric with the axis AC of the third end plate 60. In addition, eight connecting grooves 65 are formed in the surface 60a of the third end plate 60. The connecting grooves 65 extend radially outward from the inner circumferential surface of the third end plate 60 at equal 45-degree intervals in the circumferential direction and connect to the annular grooves 63, recessed toward the output shaft side OS.

[0068] 10(c) and 10(e), eight first radial grooves 61 are formed on the back surface 60b of the third end plate 60. The first radial grooves 61 extend radially outward at equal 45-degree intervals in the circumferential direction and are recessed into the anti-output-shaft AOS. Sixteen second radial grooves 62 are also formed on the back surface 60b of the third end plate 60. The second radial grooves 62 are provided two between each pair of circumferentially adjacent first radial grooves 61, and extend at an inclination in the circumferential direction as they extend radially outward. The length of the second radial grooves 62 is set shorter than the length of the first radial grooves 61.

[0069] 10(a) and 10(c), and as shown in Fig. 10(b), the radially inner ends of the first and second radial grooves 61, 62 formed in the back surface 60b overlap with the annular groove 63 formed in the front surface 60a when viewed in the axial direction. Furthermore, the first and second radial grooves 61, 62 formed in the back surface 60b and the annular groove 63 formed in the front surface 60a communicate with each other through a communication hole 67 that has a circular cross section and extends in the axial direction at the overlapping portion.

[0070] However, unlike the relationship between the first diffusion grooves 51 and the connecting grooves 55 in the second end plate 50, the eight first radial grooves 61 and sixteen second radial grooves 62 formed in the back surface 60b do not coincide in circumferential position with the eight connecting grooves 65 formed in the front surface 60a. In other words, the communicating holes 67 that communicate between the first and second radial grooves 61, 62 formed in the back surface 60b and the annular groove 63 formed in the front surface 60a do not coincide in circumferential position with the connecting grooves 65.

[0071] Furthermore, as shown in Figures 10(c) and (e), eight U-shaped discharge recesses 69 are formed on the back surface 60b of the third end plate 60 at equal intervals of 45 degrees around the circumference, with the outer peripheral edge recessed toward the AOS on the anti-output shaft side.

[0072] <Chamber space> FIG. 11 is a schematic diagram showing the second end plate 50 and the third end plate 60 stacked together. FIG. 11(a) is a cross-sectional view showing the second and third end plates 50, 60 stacked together. FIG. 11(b) is a perspective view showing the space formed by stacking the second and third end plates 50, 60. FIGS. 11(c) and 11(d) are a cross-sectional view and a perspective view, respectively, showing the rotor shaft 20 and the second and third end plates 50, 60 assembled together. FIG. 11(e) is a perspective view showing the flow of oil within the rotor shaft 20 and the second and third end plates 50, 60. In FIG. 11(a), the thicknesses of the second and third end plates 50, 60 are exaggerated relative to their diameters for clarity.

[0073] 11(a), when the back surface 50b of the second end plate 50 and the front surface 60a of the third end plate 60 are concentrically stacked in the axial direction so that the connecting grooves 55 and 65 coincide in the circumferential direction, a chamber space 43 that is circular when viewed in the axial direction and is defined by the annular grooves 53 and 63 is formed concentrically with the axis AC, as shown in FIG. 11(b). Furthermore, eight connecting flow paths 45 are also formed that are defined by the connecting grooves 55 and 65 and extend radially outward from the inner circumferential surfaces of the second and third end plates 50, 60 at equal 45-degree intervals in the circumferential direction and connect (communicate) with the chamber space 43.

[0074] 11(c), when the rotor shaft 20 is combined with the second and third end plates 50, 60 so that the eight oil discharge holes 29 and the eight connecting flow paths 45 are aligned in the circumferential direction, in other words, so that the eight oil discharge holes 29 and the eight connecting flow paths 45 are in communication with each other, the oil introduction path 20a of the rotor shaft 20 and the chamber space 43 are in communication with each other via the connecting flow paths 45, as shown in FIG. 11(d). As a result, fresh oil radially delivered from the oil introduction paths 20a of the rotor shaft 20 fills the chamber space 43.

[0075] In this way, the oil flow as shown in Figure 11(e) is realized, in other words, the part of the oil flow in the rotor 10 shown in Figure 4 that corresponds to the rotor shaft 20 and the second and third end plates 50, 60.

[0076] <First diffusion oil passage> FIG. 12 is a diagram schematically illustrating the state in which the first end plate 40 and the second end plate 50 are stacked. FIG. 12(a) is a cross-sectional view showing the state in which the first and second end plates 40, 50 are stacked. FIG. 12(b) is a perspective view showing the space formed by stacking the first and second end plates 40, 50. FIG. 12(c) is a perspective view showing the flow of oil within the rotor shaft 20 and the first to third end plates 40, 50, 60. In FIG. 11(a), the thicknesses of the first and second end plates 40, 50 are exaggerated compared to their diameters to make the drawing easier to see.

[0077] 12(a), when the back surface 40b of the first end plate 40 and the front surface 50a of the second end plate 50 are concentrically stacked in the axial direction, the first diffusion grooves 51 are covered by the back surface 40b of the first end plate 40, forming eight first diffusion oil passages 41, which are spaces extending radially at the AOS on the side opposite the output shaft from the chamber space 43, as shown in FIG. 12(b). Since each first diffusion oil passage 41 is a covered first diffusion groove 51, its radially inner end communicates with the chamber space 43 via a communication hole 57, similar to the first diffusion groove 51, and opens at the outer peripheral surface 50c of the second end plate 50, and is formed so that its cross-sectional area increases radially outward.

[0078] By forming eight such first diffusion oil passages 41, it becomes possible for a portion of the fresh oil filled in the chamber space 43 to be scattered radially outward from the outer peripheral surface 50c of the second end plate 50 by centrifugal force through these first diffusion oil passages 41. In this way, the first to third end plates 40, 50, 60 are arranged so as to overlap radially with the coil end 93a of the anti-output shaft AOS, and therefore it is possible to cool the coil end 93a, which is one of the parts to be cooled.

[0079] Furthermore, the oil that is splashed onto the coil end 93a is simply filled into the chamber space 43 formed in the second and third end plates 50, 60, which are separate from the rotor core 30, and is supplied to the coil end 93a in a sufficiently cooled state, rather than after cooling (heating) the rotor core 30, etc., thereby enabling the coil end 93a to be cooled efficiently.

[0080] Here, if the first diffusion oil passage 41 were to become clogged with oil, negative pressure would be generated within the first diffusion oil passage 41, which could result in a loss of uniformity of the oil within the chamber space 43. However, in this embodiment, the first diffusion oil passage 41 is formed so that the cross-sectional area increases as it goes radially outward, which makes it possible to prevent the first diffusion oil passage 41 from becoming clogged with oil, thereby making it possible to maintain uniformity of the oil within the chamber space 43 while cooling the coil end 93a.

[0081] In this manner, the oil flow shown in FIG. 12(c), in other words, the oil flow in the rotor 10 shown in FIG. 4, in the portions corresponding to the first to third end plates 40, 50, 60, is realized.

[0082] ≪Radial oil path≫ FIG. 13 is a schematic diagram showing the third end plate 60 attached to the rotor core 30. FIG. 13(a) is a partial perspective view showing the third end plate 60 attached to the end face 30a of the AOS on the anti-output shaft side of the rotor core 30. FIGS. 13(b) and 13(c) are cross-sectional views taken along lines bb and cc in FIG. 13(a), respectively. FIG. 13(d) is a perspective view showing the oil flow within the first to third end plates 40, 50, and 60 and within the rotor core 30. In FIG. 13(a), dashed lines indicate all areas other than the radial oil passages 61′ and 62′ for ease of viewing. In FIGS. 13(b) and 13(c), the thickness of the third end plate 60 is exaggerated compared to its diameter for ease of viewing.

[0083] As shown in FIG. 13(a), when the back surface 60b of the third end plate 60 is attached by welding or the like to the end surface 30a of the anti-output-shaft AOS of the rotor core 30 so that the first radial grooves 61 and the center lines of the magnetic poles (so-called d-axes) coincide in the circumferential direction, the first radial grooves 61 are covered by the end surface 30a of the anti-output-shaft AOS of the rotor core 30, forming eight first radial oil passages 61' extending radially on the output-shaft-side OS beyond the chamber space 43, as shown in FIG. 13(b). Since each first radial oil passage 61' is a covered first radial groove 61, its radially inner end communicates with the chamber space 43 via a communication hole 67, similar to the first radial groove 61. The length of each first radial oil passage 61' is set so that its radially outer end communicates with the gap 31c of the magnet hole 31.

[0084] Furthermore, the second radial grooves 62 are also covered by the end face 30a of the anti-output-shaft-side AOS of the rotor core 30, resulting in the formation of sixteen second radial oil passages 62' that extend at an inclination in the circumferential direction as they move radially outward on the output-shaft-side OS relative to the chamber space 43. Since each second radial oil passage 62' is a covered second radial groove 62, its radially inner end communicates with the chamber space 43 via the communication hole 67, similar to the second radial groove 62. The length and inclination direction of each second radial oil passage 62' are set so that its radially outer end communicates with the gap 36a (or gap 33b) of the magnet hole 36.

[0085] FIG. 14 is a cross-sectional view schematically showing a main portion of the rotor core 30. In FIG. 14(a), oil is indicated by the blackened portions. FIG. 14(b) shows a state in which centrifugal force acts on the oil shown in FIG. 14(a). In the rotor structure of this embodiment, by forming these eight first radial oil passages 61′ and 16 second radial oil passages 62′, oil flows through the rotor core 30 from the anti-output-shaft side AOS to the output-shaft side OS through the 24 gaps 31c, 33b, and 36a (inside the magnet holes 31, 33, and 36), as shown by the blackened portions in FIG. 13(a).

[0086] In this way, the oil flows axially inside the rotor core 30 through the multiple gaps 31c, 33b, 36a, and the oil can directly cool the permanent magnets 101, 102, 103, 106, which are one of the parts to be cooled. This allows the permanent magnets 101, 102, ... to be cooled more efficiently than, for example, a structure in which oil flows through holes (oil passages) provided in the rotor core 30 near the permanent magnets 101, 102, ...

[0087] Furthermore, in the rotor structure of this embodiment, oil is filled into the chamber space 43 from the oil inlet passage 20a of the rotor shaft 20, and the oil is distributed from the chamber space 43 to the multiple gaps 31c, 33b, and 36a.Therefore, compared to a structure in which oil is sent directly from the oil inlet passage 20a to the gaps 31c, 33b, and 36a, for example, the oil can be distributed evenly to the multiple gaps 31c, 33b, and 36a.

[0088] As described above, the communication holes 67 that connect the first and second radial grooves 61, 62 formed in the rear surface 60b with the annular groove 63 formed in the front surface 60a are not positioned in the circumferential direction as the connecting groove 65. Therefore, fresh oil that passes through the eight connecting flow paths 45 and fills the chamber space 43 is more likely to flow evenly to the eight first radial oil passages 61' and the 16 second radial oil passages 62', which makes it possible to more evenly distribute oil to the multiple gaps 31c, 33b, 36a.

[0089] Moreover, the oil distributed to the gaps 31c, 33b, 36a is simply filled once in the chamber space 43 formed in the second and third end plates 50, 60, which are separate from the rotor core 30, and is supplied to the gaps 31c, 33b, 36a in a sufficiently cooled state, rather than after cooling (raising the temperature of) the rotor core 30, etc., so that the permanent magnets 101, 102, ... can be effectively cooled. This makes it possible to prevent the permanent magnets 101, 102, ... from being insufficiently cooled, and therefore to prevent the permanent magnets 101, 102, ... from being demagnetized, and ultimately to prevent a decrease in torque.

[0090] In addition, in the rotor structure of this embodiment, as described above, the rotor core 30 is so-called skewless, which reduces the flow resistance of the oil flowing through the gaps 31c, 33b, 36a, thereby allowing the permanent magnets 101, 102, etc. to be cooled even more efficiently.

[0091] In this embodiment, as shown in Figure 14(a), no oil is flowed into the gaps 34a, 35a (the permanent magnets 104, 105 are not targeted for cooling). This is because if too much oil is flowed from the chamber space 43 toward the rotor core 30, the amount of fresh oil supplied to the coil end 93a will be reduced too much, and because the permanent magnets 101, 102, 103, 106 closer to the stator 90 are more likely to reach higher temperatures than the permanent magnets 104, 105 farther from the stator 90.

[0092] During motor operation, when cooling is required more, rotor 10 is constantly rotating, and centrifugal force (see the thick arrows in FIG. 14(b)) acts on the oil. As a result, oil flowing axially through gaps 31c, 33b, and 36a (inside magnet holes 31, 33, and 36) also tends to collect in the radially outer portions of gaps 31c, 33b, and 36a, as shown in FIG. 14(b). For this reason, if the radially outer ends of first and second radial oil passages 61′ and 62′ were connected to the radially outer portions of gaps 31c, 33b, and 36a where oil collects, it is conceivable that it would be difficult for oil to be smoothly introduced into gaps 31c, 33b, and 36a.

[0093] Furthermore, while oil flows radially outward through the first and second radial oil passages 61', 62', it flows axially when supplied to the gaps 31c, 33b, 36a. If the surface (referred to as the "first partition surface") 61a, 62a that separates the first and second radial oil passages 61', 62' at the anti-output shaft side AOS and the surface (referred to as the "second partition surface") 61b, 62b that separates the first and second radial oil passages 61', 62' radially outward are perpendicular to each other, it is possible that the oil may not change direction smoothly. In addition, as described above, centrifugal force also acts on the oil, so that the oil flowing radially through the first and second radial oil passages 61', 62' is likely to be pressed against the second partition surfaces 61b, 62b. Therefore, if the first partition surfaces 61a, 62a and the second partition surfaces 61b, 62b are perpendicular to each other, it is expected that the oil will have even more difficulty changing direction.

[0094] Therefore, in the rotor structure of this embodiment, the radially outer ends of the first and second radial oil passages 61', 62' are connected to the radially inner portions of the gaps 31c, 33b, 36a, and the first partition surfaces 61a, 62a and the second partition surfaces 61b, 62b are connected in an R-shape when viewed circumferentially.

[0095] Fig. 15 is a perspective view schematically showing the first and second radial oil passages 61', 62'. In this embodiment, as shown in Figs. 13(b) and (c) and 15(a), the radially outer ends of the first and second radial oil passages 61', 62' communicate with the radially inner portions of the gaps 31c, 33b, 36a, in other words, communicate with the portions of the gaps 31c, 33b, 36a where oil does not collect. This allows oil to be smoothly introduced from the first and second radial oil passages 61', 62' into the gaps 31c, 33b, 36a.

[0096] 13(b) and 13(c) and 15(b), the first section surfaces 61a, 62a and the second section surfaces 61b, 62b are connected by the R-shaped portions 61c, 62c when viewed in the circumferential direction, so that under centrifugal force, the oil that flows radially outward through the first and second radial oil passages 61′, 62′ can be smoothly redirected in the axial direction when it is supplied to the gaps 31c, 33b, 36a. This allows the permanent magnets 101, 102, 103, 106, which are one of the parts to be cooled, to be cooled more efficiently.

[0097] In this way, the oil flow shown in Figure 13(d) is realized, in other words, the part of the oil flow in the rotor 10 shown in Figure 4 that corresponds to the second and third end plates 50, 60 and the rotor core 30.

[0098] <End plate on the output shaft side> 1, 3, and 4, the end plates attached to the end of the output shaft side OS of rotor core 30 include fourth and fifth end plates 70, 80. In relation to the claims, the fourth and fifth end plates 70, 80 of this embodiment correspond to what is referred to in the present invention as "annular other-side end plates attached to the other axial end of the rotor core, concentrically with the axis of the rotor core."

[0099] The fourth and fifth end plates 70, 80, like the first to third end plates 40, 50, 60, are annular plates made of aluminum and have outer shapes that are the same as the outer and inner peripheral surfaces of rotor core 30. They are assembled by welding or the like to form the end plates of the output-shaft-side OS. As shown in FIG. 1, the fourth and fifth end plates 70, 80 are arranged so as to overlap, in the radial direction, with the coil end 93b of the output-shaft-side OS, which is one of the parts to be cooled.

[0100] <Fourth end plate> FIG. 16 is a schematic diagram of the fourth end plate 70. FIG. 16(a) is a diagram showing the surface (front surface 70a) of the AOS on the side opposite the output shaft. FIG. 16(b) is a cross-sectional view taken along line bb in FIGS. 16(a) and 16(c). FIG. 16(c) is a diagram showing the surface (back surface 70b) of the OS on the output shaft. In FIG. 16(b), the thickness of the fourth end plate 70 is exaggerated compared to its diameter for ease of viewing.

[0101] 16(a) to 16(c), eight outer through holes 71 are formed in the fourth end plate 70 at equal 45-degree intervals in the circumferential direction and penetrating the fourth end plate 70. The radial positions of these outer through holes 71 correspond to the eight voids 31c, respectively. In addition, sixteen inner through holes 73, which have larger diameters than the outer through holes 71 and penetrate the fourth end plate 70 radially inward of the outer through holes 71, are formed in the fourth end plate 70. The radial positions of these inner through holes 73 correspond to the sixteen voids 33b, 36a, respectively.

[0102] As shown in Figure 16(a), eight U-shaped discharge recesses 79, each with its outer periphery recessed toward the output-shaft side AOS, are formed on the front surface 70a of the fourth end plate 70 at equal 45-degree intervals in the circumferential direction. Meanwhile, as shown in Figure 16(c), communication grooves 75, 77, each trapezoidal when viewed in the axial direction, are formed on the back surface 70b of the fourth end plate 70, protruding radially outward from the outer through-hole 71 and the inner through-hole 73 and recessed toward the anti-output-shaft side AOS.

[0103] <5th end plate> Fig. 17 is a diagram schematically illustrating the fifth end plate 80. Fig. 17(a) is a diagram illustrating the surface (front surface 80a) of the AOS on the side opposite the output shaft. Fig. 17(b) is a perspective view illustrating the second diffusion grooves 81, 83. The surface (back surface 80b (see Fig. 18)) of the output shaft side OS of the fifth end plate 80 is formed flat and has no distinctive features, so a detailed description thereof will be omitted.

[0104] 17(a) and 17(b), eight second short diffusion grooves 81 are formed on the surface 80a of the fifth end plate 80. The second short diffusion grooves 81 extend radially outward at equal 45-degree intervals in the circumferential direction and are recessed toward the output shaft side OS. The radially inner ends of the second short diffusion grooves 81 are aligned approximately with the outer through-holes 71, and the second short diffusion grooves 81 extend to the outer peripheral surface 80c of the fifth end plate 80 and open at this outer peripheral surface 80c. The second short diffusion grooves 81 are formed so that their groove width increases radially outward.

[0105] Additionally, sixteen second long diffusion grooves 83 are formed on the surface 80a of the fifth end plate 80. The second long diffusion grooves 83 extend radially outward, are recessed toward the output shaft side OS, and are longer than the second short diffusion grooves 81. The radially inner ends of the second long diffusion grooves 83 are aligned with the inner through-holes 73, and extend to the outer peripheral surface 80c of the fifth end plate 80, where they open. Similar to the second short diffusion grooves 81, the second long diffusion grooves 83 are formed so that their groove width increases radially outward.

[0106] <Second diffusion oil path> FIG. 18 is a schematic diagram showing the fourth end plate 70 and the fifth end plate 80 stacked together. FIG. 18(a) is a partial perspective view showing the fourth end plate 70 and the fifth end plate 80 stacked together. FIG. 18(b) is a perspective view showing the space formed by stacking the fourth and fifth end plates 70, 80. FIGS. 18(c) and 18(d) are cross-sectional views showing the fourth and fifth end plates 70, 80 attached to the rotor core 30, corresponding to the cross-sectional views taken along lines cc and dd in FIG. 18(a), respectively. FIG. 18(e) is a perspective view showing the flow of oil within the rotor core 30 and the fourth and fifth end plates 70, 80. In FIGS. 18(c) and 18(d), the thicknesses of the fourth and fifth end plates 70, 80 are exaggerated relative to their diameters for clarity.

[0107] As shown in Figure 18(a), when the back surface 70b of the fourth end plate 70 and the front surface 80a of the fifth end plate 80 are concentrically stacked in the axial direction, the second short diffusion grooves 81 are covered by the back surface 70b of the fourth end plate 70, forming eight second short diffusion oil passages 81' that are radially extending spaces, as shown in Figure 18(b). Since each second short diffusion oil passage 81' is a covered second short diffusion groove 81, like the second short diffusion groove 81, its radially inner end communicates with the outer through-hole 71 and opens at the outer peripheral surface 80c of the fifth end plate 80, and is formed so that its cross-sectional area increases radially outward.

[0108] Similarly, the second long diffusion grooves 83 are covered by the back surface 70b of the fourth end plate 70, thereby forming 16 second long diffusion oil passages 83', which are spaces extending in the radial direction. Since each second long diffusion oil passage 83' is a covered second long diffusion groove 83, like the second long diffusion groove 83, its radially inner end communicates with the inner through-hole 73 and opens at the outer peripheral surface 80c of the fifth end plate 80, and is formed so that its cross-sectional area increases radially outward.

[0109] When the surface 70a of the fourth end plate 70 is attached by welding or the like to the end face 30b of the output shaft side OS of the rotor core 30 so that the outer through hole 71 and the gap 31c (the inner through hole 73 and the gaps 33b, 36a) are aligned in the circumferential direction, the second short diffusion oil passage 81' and the gap 31c are connected via the outer through hole 71, and the second long diffusion oil passage 83' and the gaps 33b, 36a are connected via the inner through hole 73, as shown in Figure 18(c).

[0110] FIG. 19 is a perspective view schematically illustrating the outer and inner through-holes 71 and 73. However, because oil flows axially through the gaps 31c, 33b, and 36a and radially outward through the second short diffusion oil passages 81′ and the second long diffusion oil passages 83′, it is possible that the oil may not change direction smoothly. Therefore, in the rotor structure of this embodiment, R-shaped communication grooves 75 and 77 are formed in the circumferential direction at the portions where the second short diffusion oil passages 81′ and the second long diffusion oil passages 83′ communicate with the outer and inner through-holes 71 and 73. This allows oil to be smoothly introduced from the gaps 31c, 33b, and 36a into the second short diffusion oil passages 81′ and the second long diffusion oil passages 83′.

[0111] The formation of such second short diffusion oil passages 81' and second long diffusion oil passages 83' enables oil that has flowed through gaps 31c, 33b, and 36a to be scattered radially outward from outer peripheral surface 80c of fifth end plate 80 by centrifugal force through second short diffusion oil passages 81' and second long diffusion oil passages 83'. Thus, because the fourth and fifth end plates 70, 80 are arranged to overlap with coil end 93b of output shaft side OS in the radial direction, it is possible to cool coil end 93b of output shaft side OS, which is one of the parts to be cooled.

[0112] Similarly to first diffusion oil passage 41, second short diffusion oil passage 81' and second long diffusion oil passage 83' are also formed so that their cross-sectional areas increase radially outward, which prevents second short diffusion oil passage 81' and second long diffusion oil passage 83' from being blocked by oil. This prevents a phenomenon in which the amount of oil flowing through magnet holes communicating with second short diffusion oil passage 81' and second long diffusion oil passage 83' where negative pressure is generated increases, thereby preventing the even distribution of oil from being impaired.

[0113] Here, unlike the coil end 93a of the AOS on the anti-output shaft side, the coil end 93b of the OS on the output shaft side is supplied with oil (that has been heated to a certain extent) after cooling the rotor core 30, etc. However, since the number (24) of second short diffusion oil passages 81' and second long diffusion oil passages 83' is set to be greater than the number (8) of first diffusion oil passages 41, in other words, the amount of oil supplied to the coil end 93b is relatively greater, and therefore the coil end 93b can also be cooled efficiently.

[0114] In this way, the oil flow shown in Figure 18(e) is realized, in other words, the part of the oil flow in the rotor 10 shown in Figure 4 that corresponds to the rotor core 30 and the fourth and fifth end plates 70, 80.

[0115] In the above rotor structure, the rotor core 30 is sandwiched axially between the third end plate 60 and the fourth end plate 70, but because the rotor core 30 is a laminate of stacked magnetic thin plates, it is possible that oil flowing axially inside the rotor core 30 may leak into the gaps between the magnetic thin plates. In this case, it may seem that the leaked oil would have nowhere to escape because it is sandwiched between the third end plate 60 and the fourth end plate 70. However, in this embodiment, the third and fourth end plates 60, 70 are formed with discharge recesses 69, 79, so that oil that leaks into the gaps between the magnetic thin plates can be discharged to the outside of the rotor core 30 through these discharge recesses 69, 79.

[0116] (Other embodiments) The present invention is not limited to the embodiments, and can be implemented in various other forms without departing from the spirit or main characteristics thereof.

[0117] In the above embodiment, the permanent magnets 101, 102, 103, and 106 and the coil ends 93a and 93b are the parts to be cooled, but this is not limitative. For example, a separate cooling means may be used for the coil ends 93a and 93b, and only the permanent magnets 101, 102, 103, and 106 may be cooled.

[0118] Furthermore, in the above embodiment, four of the six permanent magnets 101, 102, 103, 104, 105, 106 that constitute each magnetic pole are targeted for cooling, but this is not limiting. For example, as shown in FIG. 20(a), a radial oil passage 62" that communicates with the chamber space 43 may be provided, and oil may also be caused to flow into the gaps 34a and 35a as shown by the blackened areas in FIG. 20(b), so that the permanent magnets 104 and 105 are targeted for cooling. In addition, as shown by the blackened areas in FIG. 20(c), oil may also be caused to flow into the gaps 31a, 31e, 37a that are not in contact with the permanent magnets 101, 102, 103, 104, 105, 106, so that the permanent magnets 103 and 106 are indirectly cooled.

[0119] Furthermore, in the above embodiment, the rotor core 30 is so-called skewless. However, this is not limiting. For example, the present invention may be applied to a rotor core 30' having a skew angle θ, which is formed by combining four laminates 30A', 30B', 30C', and 30D', each of which is made by stacking a predetermined number of magnetic thin plates in the axial direction, with each laminate being shifted by an angle θ, as shown in FIG.

[0120] In addition, in the above embodiment, the number of oil discharge holes 29, connecting flow paths 45, first diffusion oil passages 41, first radial oil passages 61', second short diffusion oil passages 81', etc. is eight, and the number of second radial oil passages 62', second long diffusion oil passages 83', etc. is 16, but this is not limited to this and these numbers may be set appropriately.

[0121] Furthermore, in the above embodiment, the rotor 10 has eight magnetic poles, but this is not limiting, and for example, the number of magnetic poles may be less than eight, or may be more than eight.

[0122] In addition, in the above embodiment, each magnetic pole has a two-layer structure with an outer embedded magnet section 100A arranged in a V-shape on the radially outer side and an inner embedded magnet section 100B arranged in a U-shape on the radially inner side, but this is not limited to this, and it may also have a single-layer structure with outer embedded magnet sections arranged in a V-shape or a straight line, for example.

[0123] Furthermore, in the above embodiment, the end plates of the anti-output shaft side AOS are formed by the first to third end plates 40, 50, 60, and the end plates of the output shaft side OS are formed by the fourth and fifth end plates 70, 80, but this is not limited to this, and the end plates of the anti-output shaft side AOS and the output shaft side OS may each be formed from a single member, for example, using a sand mold for casting.

[0124] As such, the above-described embodiments are merely examples in all respects and should not be interpreted as limiting. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0125] According to the present invention, the parts to be cooled inside a synchronous motor can be efficiently cooled, and therefore, it is extremely useful when applied to the rotor structure of a synchronous motor. [Explanation of symbols]

[0126] 1. Synchronous motor 10 rotors 20 rotor shaft 30 rotor core 31, 33, 36 Magnet holes 40 First end plate (one side end plate) 41 First diffusion oil channel 43 Chamber space 50 Second end plate (one side end plate) 50c outer surface 60 Third end plate (one side end plate) 61' 1st radial oil passage 61a, 62a First partition surface (surface dividing the radial oil passage on one side of the axial direction) 62' 2nd radial oil passage 61b, 62b Second partition surface (surface dividing the radial oil passage on the radial outer side) 70 4th end plate (other end plate) 80 5th end plate (other end plate) 81' Second short diffusion oil passage (Second diffusion oil passage) 83' Second long diffusion oil passage (Second diffusion oil passage) 90 Stator 93 Stator coil 93a, 93b Coil end (cooling target part) 101, 102 outer permanent magnet (part to be cooled) 103, 106 Inner permanent magnet (part to be cooled)

Claims

1. A rotor structure that supplies oil to a cooling target inside a synchronous motor in which the rotor rotates in synchronization with a rotating magnetic field generated by a stator, The rotor has a plurality of permanent magnets, which are one of the cooling targets, and a cylindrical rotor core in which the permanent magnets are embedded and in which a plurality of axially extending magnet holes are formed, and is configured so that oil flows axially inside the rotor core through the plurality of magnet holes.

2. 2. The rotor structure according to claim 1, the rotor further includes a rotor shaft inserted into the rotor core so as to be unable to rotate relative to the rotor core, and a circular one-side end plate attached to one axial end of the rotor core concentrically with an axis of the rotor core, a chamber space having an annular shape when viewed in the axial direction is formed in the one end plate and is concentric with the axis of the rotor core, A rotor structure characterized in that the one-side end plate is configured so that oil is filled into the chamber space from an oil passage in the rotor shaft and oil is distributed from the chamber space to the multiple magnet holes.

3. In the rotor structure according to claim 2, a plurality of radial oil passages are formed in the one-side end plate, the radial oil passages extending radially on the other axial side of the chamber space, the radially inner ends of the radial oil passages communicating with the chamber space, and the radially outer ends of the radial oil passages communicating with the plurality of magnet holes; A rotor structure characterized in that each of the above-mentioned radial oil passages has a surface that defines the radial oil passage on one axial side and a surface that defines the radial oil passage on the radially outer side, which are connected in an R-shape when viewed circumferentially.

4. In the rotor structure according to claim 2, a plurality of radial oil passages are formed in the one-side end plate, the radial oil passages extending radially on the other axial side of the chamber space, the radially inner ends of the radial oil passages communicating with the chamber space, and the radially outer ends of the radial oil passages communicating with the plurality of magnet holes; A rotor structure characterized in that the radially outer end of each of the radial oil passages is in communication with the radially inner portion of each of the magnet holes.

5. In the rotor structure according to claim 2, the one-side end plate is disposed so as to overlap, as viewed in the radial direction, a coil end on one axial side of the stator coil attached to the stator, which is one of the cooling targets; The one-side end plate is formed with a plurality of first diffusion oil passages, each extending radially on one axial side of the chamber space, each having a radially inner end communicating with the chamber space and opening at an outer peripheral surface of the one-side end plate, A rotor structure characterized in that each of the first diffusion oil passages is formed so that the cross-sectional area increases as it goes radially outward.

6. In the rotor structure according to claim 5, the rotor further includes an annular other-side end plate attached to an end portion of the rotor core on the other axial side and concentric with an axis of the rotor core, the other-side end plate is disposed so as to overlap, as viewed in the radial direction, a coil end on the other axial side of the stator coil, which is one of the cooling targets, The other end plate is provided with a plurality of second diffusion oil passages extending radially, each of which has a radially inner end communicating with the plurality of magnet holes, which opens at an outer peripheral surface of the other end plate, and whose cross-sectional area increases as it extends radially outward. A rotor structure characterized in that the number of the second diffusion oil passages is set to be greater than the number of the first diffusion oil passages.

7. 2. The rotor structure according to claim 1, A rotor structure characterized in that the rotor core has a skew angle of 0 degrees.

Images