Rotor Structure

Abstract

A rotor structure capable of efficiently cooling a part to be cooled inside a synchronous motor is provided. [Solution] This rotor structure supplies oil to parts to be cooled inside a synchronous motor in which a rotor (10) rotates in synchronization with a rotating magnetic field generated by a stator. The rotor (10) includes a plurality of permanent magnets (101, 102, 103, 106) which are parts to be cooled, and a cylindrical rotor core (30) in which a plurality of magnet holes (31) extending in the axial direction are formed, and in which the permanent magnets (101, 102) are embedded. The rotor (10) is configured so that oil flows axially inside the rotor core (30) through the plurality of magnet holes (31).

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 the motors that drive them to be easier to install and more productive, easier to deploy in a wide range of vehicle models, and cheaper to manufacture. To achieve these goals, there is a demand to reduce the size of the motor while maintaining its output, in other words, to increase the output density of the motor.

[0003] In order to increase the output density of a motor, it is unavoidable to increase 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, Patent Document 1, for example, discloses a rotor for a rotating electric machine in which a coolant flow passage extending in the axial direction is provided near the magnets housed in the rotor core. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-176235 A 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 the above-mentioned 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, the configuration of 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 consideration of the above-mentioned points, and an object of the present invention is to provide a rotor structure capable of efficiently cooling the parts to be cooled inside a synchronous motor. [Means for solving the problem]

[0008] In order to achieve the above object, in a 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 a stator.

[0010] The rotor structure includes a plurality of permanent magnets, which are one of the cooling targets, a cylindrical rotor core in which the permanent magnets are embedded and in which a plurality of magnet holes extending in the axial direction are formed, a rotor shaft that is inserted into the rotor core so as not to rotate relative to the rotor core; and an annular one-side end plate that is attached to one end of the rotor core in an axial direction and concentric with an axis of the rotor core; Equipped with In addition, in the one end plate, a chamber space having an annular shape when viewed in the axial direction is formed concentrically with the axis of the rotor core, and a plurality of connecting flow paths extending radially on the radial inside of the chamber space and communicating with an oil passage in the rotor shaft and a plurality of radial oil paths extending radially and communicating with the chamber space and a plurality of the magnet holes are formed so as to be shifted from each other in the circumferential direction and the axial direction, and oil is filled into the chamber space from the oil passage in the rotor shaft via the plurality of connecting flow paths, and oil is distributed from the chamber space via the plurality of radial oil paths. Oil is multiple the above Through the magnet bore the above It is characterized in that it is configured so that the fluid flows axially inside the rotor core.

[0011] According to this configuration, the oil flows axially inside the rotor core through the magnet holes in which the permanent magnets are embedded, and the oil can directly cool the permanent magnets, which are one of the objects to be cooled. This makes it possible to cool the permanent magnets, which are one of the objects 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, when oil is sent to the rotor, it is common to send the oil from an oil passage provided in the rotor shaft, but if a configuration is adopted in which the oil passage in the rotor shaft is directly connected to the magnet holes, it is possible that there will be variations in the amount of oil supplied to the magnet holes. If such variations in the amount of oil occur, some of the permanent magnets embedded in the rotor core will not be sufficiently cooled, and some of the permanent magnets may be demagnetized, resulting in a decrease in torque.

[0014] this Point above According to this configuration, rather than 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 the multiple magnet holes, allowing oil to be evenly supplied to the multiple magnet holes formed in the rotor core.

[0015] Furthermore, the oil distributed to the magnet hole is only filled into the chamber space once, and is supplied to the magnet hole in a sufficiently cooled state, rather than after cooling (raising the temperature) the rotor core, etc., so that 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] In addition, in the above rotor structure, A plurality of the radial oil passagesextends radially on the other axial side of the chamber space, and has a radially inner end communicating with the chamber space and a radially outer end communicating with the plurality of magnet holes. As shown above, on one end plate Each of the radial oil passages may be formed such that 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 are connected in an R-shape when viewed in the circumferential direction.

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

[0019] Here, the oil flows radially outward in the radial oil passage, but flows axially when supplied to the magnet hole, and if a surface that divides the radial oil passage on one axial side (referred to as the "first section screen") and a surface that divides the radial oil passage on the radial outside (referred to as the "second section screen") are perpendicular to each other, it is assumed that the oil will not change direction smoothly. In addition, during motor operation when the need for cooling is high, the rotor is constantly rotating and centrifugal force acts on the oil, so the oil that flows radially in the radial oil passage is easily pressed against the second section screen, and it is assumed that in a structure in which the first section screen and the second section screen are perpendicular to each other, it will be even more difficult for the oil to change 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 in the circumferential direction, so that under centrifugal force, the oil that flows radially outward through the radial oil passage can be smoothly redirected in the axial direction when it is supplied to the magnet hole, thereby making it possible to more efficiently cool the permanent magnets, which are the parts to be cooled.

[0021] Furthermore, in the above rotor structure, A plurality of the radial oil passagesextends radially on the other axial side of the chamber space, and has a radially inner end communicating with the chamber space and a radially outer end communicating with the plurality of magnet holes. As shown above, on one end plate a radially outer end of each of the radial oil passages may be formed in the magnet hole, and the radially outer end of each of the radial oil passages may be communicated with a radially inner portion of each of the magnet holes.

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

[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, connected to the portion of the magnet hole where oil is less likely to collect, so that 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 a 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 as to have a cross-sectional area that increases radially outward.

[0025] According to this configuration, a plurality of first diffusion oil passages are formed that extend radially on one axial side of the chamber space (the opposite side of the rotor core across the chamber space), have radially inner ends that communicate with the chamber space, and open on the outer circumferential surface of the one-side end plate, so that a portion of the oil filled in the chamber space can be scattered radially outward from the outer circumferential 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 disposed so as to overlap the coil end on one axial side when viewed in the radial direction, 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, like the oil distributed to the magnet holes, is simply filled into the chamber space once, and is supplied to the coil ends in a sufficiently cooled state, rather than after cooling (heating) the rotor core, etc., so that not only the permanent magnets but also the coil ends can be cooled efficiently.

[0027] Here, if the first diffusion oil passage were to become clogged with oil, negative pressure would be generated within the first diffusion oil passage, which would cause the uniformity of the oil in the chamber space to be lost, and it is possible that the even distribution of the oil to the multiple magnet holes would be hindered. In this regard, in this configuration, the first diffusion oil passage is formed so that the cross-sectional area increases as it moves radially outward, which makes it possible to prevent the first diffusion oil passage from becoming clogged with oil, and thus makes it possible to maintain efficient cooling of the permanent magnets while cooling the coil ends.

[0028] Furthermore, in the above 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 coil end on the other axial side of the stator coil, which is one of the cooling targets, and the other-side end plate is formed with a plurality of second diffusion oil passages extending radially, having radially inner ends communicating with the plurality of magnet holes, opening at the outer peripheral surface of the other-side end plate, and having 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] According to this configuration, as in the case of 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 the cross-sectional area increases as it goes radially outward, so that it is possible to prevent the second diffusion oil passage from being blocked by oil, and thus it is possible to prevent the occurrence of a phenomenon in which the amount of oil flowing through the magnet hole communicating with the second diffusion oil passage where negative pressure is generated increases, thereby impairing the even distribution of oil.

[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 efficiently cooled.

[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 to the oil flowing inside the magnet hole can be reduced, thereby making it possible to more efficiently cool the permanent magnets, which are the parts to be cooled. Effect 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 description of the drawings]

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

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

[0036] -Motor Overview- Fig. 1 is a vertical cross-sectional view showing a schematic overview of 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 Fig. 1, for the stator 90, in order to make the drawing easier to see, a detailed cross section of a stator core 91 is not shown, and only the outer shape of the stator core 91 and coil ends 93a, 93b of a stator coil 93 attached to the stator core 91 are shown.

[0037] The synchronous motor 1 of this embodiment is mounted, for example, on an electric vehicle, and as shown in Figure 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 section 21 and a shaft main body 27, and an oil introduction passage 20a through which oil flows is formed therein. In addition to the rotor shaft 20 and the rotor core 30, the rotor 10 has permanent magnets 101, 102, 103, 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, 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 an outline of the synchronous motor 1, and since emphasis is placed on ease of understanding, the circumferential positions of the components in the rotor 10 are not necessarily aligned.

[0039] -Cooling System- Fig. 2 is a block diagram for explaining a schematic example of a cooling system 2 in an electric vehicle. As shown in Fig. 2, the 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 cooling water circulates, and an inverter 5, a radiator 6, and a water pump 7 for circulating the cooling water, 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 cooling water, and the heat absorbed by the cooling water is dissipated to the outside by the radiator 6, thereby maintaining the cooling water and the inverter 5 at low temperatures.

[0041] On the other hand, the motor cooling system 4 has a circulation path 4a through which oil circulates, and the motor 1 and an oil pump 9 that pumps oil to the oil introduction section 21 of the rotor shaft 20, each of which is provided on the circulation path 4a. In this motor cooling system 4, heat generated in the synchronous motor 1 is absorbed by the oil, and the oil that has absorbed the heat accumulates 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 cooling water through indirect heat exchange between the circulation paths 3a and 4a in the heat exchanger 8, and then the heat is dissipated 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 sends oil maintained at a relatively low temperature (for convenience, also referred to as “fresh oil”) to the oil introduction portion 21 of the rotor shaft 20.

[0043] -Outline of rotor structure- Fig. 3 is a perspective view showing a space in the rotor 10 through which the oil flows, and Fig. 4 is a perspective view showing a direction in which the oil flows 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 in the second and third end plates 50, 60 and is directly supplied to the gap 31a in the magnet hole 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 arrow in Fig. 1, so that the permanent magnets 101, 102, ... are efficiently cooled.

[0044] Similarly, fresh oil is supplied directly to the coil end 93a of the AOS on the opposite side of the axial output shaft (hereinafter simply referred to as the "opposite side 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 coil end 93b of the OS on the opposite side of the axial output shaft (hereinafter simply referred to as the "output shaft OS"), which is one of the parts to be cooled, is also efficiently cooled by the oil after cooling the permanent magnets 101, 102, ...

[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, ... to be supplied to the target part to be cooled.

[0046] The rotor structure that enables 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 a central hole 38 (see FIG. 8) of the cylindrical rotor core 30 so as to be non-rotatable 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 anti-output shaft side AOS 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 showing a schematic of the oil introduction part 21. FIG. 5(a) is a perspective view of the oil introduction part 21. FIG. 5(b) is a diagram showing a surface of the oil introduction part 21 on the output shaft side OS. FIG. 5(c) is a cross-sectional view taken along the line cc in FIG. 5(a). As shown in FIG. 5(a), the oil introduction part 21 is formed in such a shape that a cylindrical small diameter part 22 and a cylindrical large diameter part 23 having an outer diameter larger than that of the small diameter part 22 are connected in the axial direction via a stepped surface so as to be 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 through their axial centers. In addition, a recess 25 having a circular cross section that is recessed into the AOS on the counter-output shaft side is formed at the end of the output shaft side OS of the large diameter portion 23, as shown in Figs. 5(a) to (c). The recess 25 communicates with the oil introduction hole 24 at its center. In addition, eight oil discharge grooves 26 that are recessed into the AOS on the counter-output shaft side are formed at the end of the output shaft side OS of the large diameter portion 23, as shown in Figs. 5(a) and (b), extending radially outward from the recess 25 at equal intervals of 45 degrees in the circumferential direction. The radially inner end of each oil discharge groove 26 communicates with the recess 25, and the radially outer end opens on the outer circumferential surface of the large diameter portion 23.

[0050] <Shaft body> Fig. 6 is a diagram showing a schematic view of a main part of the shaft main body 27. Fig. 6(a) is a perspective view of a main part 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 the inner diameter is set to be slightly larger than the outer diameter of the large diameter portion 23.

[0051] As shown in Figs. 6(a) and (c), the shaft 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 AOS of the shaft body 27 to the surface of the anti-output-shaft AOS of the partition plate 28 is set to the same length as the axial length of the large-diameter portion 23. Also, as shown in Figs. 6(a) and (b), the shaft body 27 is formed with eight oil discharge holes 29 that extend radially outward at equal intervals of 45 degrees in the circumferential direction and penetrate the shaft body 27. The oil discharge holes 29 are circular holes with a diameter substantially equal to the depth of the oil discharge groove 26, and are formed at positions that contact the surface of the anti-output-shaft AOS of the partition plate 28.

[0052] <Oil inlet passage> FIG. 7 is a schematic diagram of the rotor shaft 20. FIG. 7(a) is a perspective view of a main part of the shaft main body 27. FIG. 7(b) is a cross-sectional view taken along the line bb in FIG. 7(a). FIG. 7(c) is a cross-sectional view taken along the line cc in FIG. 7(a). FIG. 7(d) is a perspective view showing the flow of oil in the rotor shaft 20. The rotor shaft 20 is a combination of the oil introduction part 21 and the shaft main body 27 configured as described above. Specifically, the rotor shaft 20 is configured by fitting the large diameter part 23 into the hollow part 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 introduction portion 21 and the shaft main body portion 27 are combined, the recess 25 and the oil discharge groove 26 are covered by the surface of the partition plate 28 on the side AOS opposite to the output shaft, and a disk-shaped space 25' and an oil discharge passage 26' having a closed cross section are formed. As a result, the oil introduction passage 20a is formed in which fresh oil flows through the oil introduction 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 passage 26' radially outward, and is then sent out radially to the outside of the rotor shaft 20 through the oil discharge hole 29.

[0054] In this manner, the oil flow as 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 showing a schematic diagram of rotor core 30 and permanent magnets 101, 102, .... FIG. 8(a) is an overall view of rotor core 30. FIG. 8(b) is an enlarged view of magnetic poles separated by dashed lines in FIG. 8(a). Rotor core 30 is a laminated body in which a predetermined number of annular magnetic thin plates formed into a predetermined shape are stacked in the axial direction, and as shown in FIG. 8(a), it is formed into a cylindrical shape having a central hole 38 to which rotor shaft 20 is fixed by shrink fitting. Note that electromagnetic steel plates, which are a type of silicon steel plate, can be used as the material for the magnetic thin plates.

[0056] In the rotor core 30, a plurality of magnet holes 31, 33, 34, 35, 36 extending in the axial direction are formed so that the number of magnetic poles of the rotor 10 is eight 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 the plurality of 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 the permanent magnets 101, 102, ... extend straight in the axial direction from the end of the AOS on the counter-output shaft side of the rotor core 30 to the end of the OS on the output shaft side. Although the positions and shapes of the magnet holes 31, 33, ... and the permanent magnets 101, 102, ... of each magnetic pole are different, the basic configuration is the same, so 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 is configured with a two-layer structure 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 in the protrusions 37 shown in Fig. 8 are intended to suppress the generation of harmonic components contained in the magnetic flux, and are not related to this embodiment, so detailed description will be omitted.

[0058] The outer embedded magnet section 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 in which the distance between them increases radially outward and decreases radially inward. The portions of the magnet hole 31 that are not filled with the two permanent magnets 101, 102 and the portions partitioned by the bridge 39 remain as gaps (flux barriers) 31a, 31b, 31c, 31d, and 31e. Of these gaps 31a, 31b, 31c, 31d, and 31e, the gap 31c serves as an oil passage through which oil flows to cool the permanent magnets 101, 102, as described below.

[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 distance between them increases toward the radially outward direction and decreases toward the radially inward direction. The portions of the magnet holes 33 and 36 that are not filled with the permanent magnets 103 and 106 remain as voids 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 voids 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, 60. In relation to the claims, the first to third end plates 40, 50, 60 of this embodiment correspond to what is referred to in the present invention as "annular one-side end plates attached concentrically to the axis of the rotor core at one axial end of the rotor core."

[0061] The first to third end plates 40, 50, 60 are annular aluminum plates having the same outer shapes as the outer and inner circumferential surfaces of the rotor core 30, and are assembled by welding or the like to form the end plates of the non-output-shaft AOS. As shown in FIG. 1, the first to third end plates 40, 50, 60 are arranged so as to overlap the coil end 93a of the non-output-shaft AOS, which is one of the parts to be cooled, when viewed in the radial direction. As shown in FIG. 12(a) below, the first end plate 40 has a flat front surface 40a (surface of the non-output-shaft AOS) and a flat back surface 40b (surface of the output-shaft OS), and does not have any special features, so a detailed description thereof will be omitted.

[0062] <Second end plate> FIG. 9 is a diagram showing the second end plate 50. FIG. 9(a) is a diagram showing the surface (front surface 50a) of the AOS on the side opposite to the output shaft. FIG. 9(b) is a cross-sectional view taken along the line bb in FIG. 9(a) and (c). FIG. 9(c) is a diagram showing the surface (rear 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 diagrams shown in the bold frames in FIG. 9(a) and (c) are partial enlarged views of the dashed frame. In FIG. 9(b), the thickness of the second end plate 50 is exaggerated in comparison with the diameter in order to make the diagram easier to see.

[0063] 9(a) and 9(d), eight first diffusion grooves 51 are formed on the surface 50a of the second end plate 50, extending radially outward at equal intervals of 45 degrees in the circumferential direction and recessed into the output shaft side OS. Each first diffusion groove 51 extends to the outer circumferential surface 50c of the second end plate 50 and opens at the outer circumferential surface 50c, and is formed so that 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, concentric with the axis AC of the second end plate 50, and recessed into the AOS on the anti-output shaft side. In addition, eight connecting grooves 55 are formed on the back surface 50b of the second end plate 50, extending radially outward from the inner circumferential surface of the second end plate 50 at equal intervals of 45 degrees in the circumferential direction and connecting to the annular groove 53.

[0065] As shown in the bold frames in Figures 9(a) and (c) and in Figure 9(b), the radially inner end of the first diffusion groove 51 formed on the front surface 50a overlaps 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. The first diffusion grooves 51 formed on the front surface 50a and the annular groove 53 formed on the back surface 50b communicate with each other through a communication hole 57 that has a circular cross section and extends in the axial direction at the overlapping portion.

[0066] <Third end plate> FIG. 10 is a diagram showing a schematic view of the third end plate 60. FIG. 10(a) is a diagram showing the surface (front surface 60a) of the AOS on the side opposite to the output shaft. FIG. 10(b) is a cross-sectional view taken along the line bb in FIG. 10(a) and (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 diagrams shown in the bold frames in FIG. 10(a) and (c) are partial enlarged views of the dashed frame. In FIG. 10(b), the thickness of the third end plate 60 is exaggerated in comparison with the diameter in order to make the diagram easier to see.

[0067] 10(c) and 10(e), a circular annular groove 63 recessed into the output shaft side OS is formed in the surface 60a of the third end plate 60, concentric with the axis AC of the third end plate 60. In addition, eight connecting grooves 65 recessed into the output shaft side OS 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 intervals of 45 degrees in the circumferential direction and connect to the annular groove 63.

[0068] 10(c) and 10(e), eight first radial grooves 61 are formed on the back surface 60b of the third end plate 60, which extend radially outward at equal intervals of 45 degrees in the circumferential direction and are recessed into the anti-output-shaft AOS. In addition, sixteen second radial grooves 62 are formed on the back surface 60b of the third end plate 60, which are provided two between each pair of circumferentially adjacent first radial grooves 61, extend at an inclination in the circumferential direction as they move radially outward, and are recessed into the anti-output-shaft AOS. 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 thick frames and 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. The first and second radial grooves 61, 62 formed in the back surface 60b communicate with the annular groove 63 formed in the front surface 60a through a communication hole 67 having a circular cross section and extending 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 the 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 communication holes 67 that communicate the first and second radial grooves 61, 62 formed in the back surface 60b with the annular groove 63 formed in the front surface 60a do not coincide in circumferential position with the connecting grooves 65.

[0071] Furthermore, on the rear surface 60b of the third end plate 60, as shown in Figures 10(c) and (e), eight U-shaped discharge recesses 69 are formed at equal intervals of 45 degrees in the circumferential direction, 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 state where the second end plate 50 and the third end plate 60 are stacked. FIG. 11(a) is a cross-sectional view showing the state where the second and third end plates 50, 60 are stacked. FIG. 11(b) is a perspective view showing a space formed by stacking the second and third end plates 50, 60. FIG. 11(c) and (d) are a cross-sectional view and a perspective view, respectively, showing the state where the rotor shaft 20 and the second and third end plates 50, 60 are combined. FIG. 11(e) is a perspective view showing the flow of oil in 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 compared to their diameters in order to make the drawing easier to see.

[0073] As shown in Fig. 11(a), when the rear 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 defined by the annular grooves 53 and 63 and has a circular shape when viewed in the axial direction is formed concentrically with the axis AC, as shown in Fig. 11(b). In addition, eight connecting flow paths 45 are also formed, which 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 intervals of 45 degrees 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 passages 45 coincide in the circumferential direction, in other words, so that the eight oil discharge holes 29 and the eight connecting passages 45 communicate with each other, the oil introduction passages 20a of the rotor shaft 20 communicate with the chamber space 43 via the connecting passages 45, as shown in FIG. 11(d). As a result, fresh oil radially sent out from the oil introduction passages 20a of the rotor shaft 20 fills the chamber space 43.

[0075] In this manner, the oil flow as shown in Figure 11(e) is realized, in other words, the portion 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 schematic diagram showing the first end plate 40 and the second end plate 50 stacked together. FIG. 12(a) is a cross-sectional view showing the first and second end plates 40, 50 stacked together. FIG. 12(b) is a perspective view showing a space formed by stacking the first and second end plates 40, 50. FIG. 12(c) is a perspective view showing the flow of oil in 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 in order to make the drawing easier to see.

[0077] As shown in Fig. 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 groove 51 is covered by the back surface 40b of the first end plate 40, and eight first diffusion oil passages 41 are formed as 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, the radially inner end of each first diffusion oil passage 41 communicates with the chamber space 43 via a communication hole 57, like the first diffusion groove 51, and is open at the outer circumferential surface 50c of the second end plate 50, and is formed so that the cross-sectional area increases as it goes radially outward.

[0078] By forming eight of these 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 circumferential surface 50c of the second end plate 50 by centrifugal force through these first diffusion oil passages 41. In addition, since the first to third end plates 40, 50, 60 are arranged so as to overlap with the coil end 93a of the anti-output shaft side AOS when viewed in the radial direction, 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 to the coil end 93a is simply filled once 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 while still in a sufficiently cooled state, rather than after cooling (raising the temperature) the rotor core 30 etc., so that the coil end 93a can be cooled efficiently.

[0080] Here, if the first diffusion oil passage 41 is blocked by oil, negative pressure will be generated in the first diffusion oil passage 41, which may cause a loss of uniformity of the oil in 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, so that it is possible to prevent the first diffusion oil passage 41 from being blocked by oil, and therefore it is possible to maintain the uniformity of the oil in the chamber space 43 while cooling the coil end 93a.

[0081] In this manner, the oil flow as shown in FIG. 12(c), in other words, the portions of the oil flow in the rotor 10 shown in FIG. 4 that correspond to the first to third end plates 40, 50, 60, are achieved.

[0082] ≪Radial oil path≫ FIG. 13 is a diagram showing a schematic state in which the third end plate 60 is attached to the rotor core 30. FIG. 13(a) is a partial perspective view showing a state in which the third end plate 60 is attached to the end surface 30a of the AOS on the opposite side of the output shaft of the rotor core 30. FIG. 13(b) and FIG. 13(c) are cross-sectional views taken along the lines bb and cc in FIG. 13(a), respectively. FIG. 13(d) is a perspective view showing the flow of oil in the first to third end plates 40, 50, and 60 and in the rotor core 30. In FIG. 13(a), the radial oil passages 61' and 62' are shown by dashed lines in order to make the drawing easier to see. In FIG. 13(b) and FIG. 13(c), the thickness of the third end plate 60 is exaggerated compared to the diameter in order to make the drawing easier to see.

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

[0084] The second radial groove 62 is also covered by the end face 30a of the AOS on the counter-output shaft side of the rotor core 30, and sixteen second radial oil passages 62' are formed, which extend at an incline in the circumferential direction toward the radially outer side on the output-shaft side OS from the chamber space 43. Since each second radial oil passage 62' is a covered second radial groove 62, the radially inner end of each second radial oil passage 62' 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 the radially outer end communicates with the gap 36a (or gap 33b) of the magnet hole 36.

[0085] FIG. 14 is a cross-sectional view showing a schematic view of a main part of the rotor core 30. In FIG. 14(a), the oil is shown as a black portion. FIG. 14(b) shows a state where centrifugal force acts on the oil shown in FIG. 14(a). In the rotor structure of this embodiment, by forming such eight first radial oil passages 61' and sixteen second radial oil passages 62', the oil flows from the anti-output shaft side AOS to the output shaft side OS inside the rotor core 30 through 24 voids 31c, 33b, 36a (in magnet holes 31, 33, 36) as shown by the black portion 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 in holes (oil paths) 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, 36a. Therefore, compared to a structure in which oil is sent directly from the oil inlet passage 20a to the gaps 31c, 33b, 36a, for example, the oil can be distributed evenly to the multiple gaps 31c, 33b, 36a.

[0088] As described above, the communication hole 67 that communicates the first and second radial grooves 61, 62 formed in the back surface 60b with the annular groove 63 formed in the front surface 60a does not coincide in circumferential position with the connecting groove 65. Therefore, fresh oil that is filled into the chamber space 43 through the eight connecting flow paths 45 tends to flow evenly to the eight first radial oil passages 61' and the sixteen second radial oil passages 62', making 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 temporarily filled in the chamber space 43 formed in the second and third end plates 50, 60 separate from the rotor core 30, and is supplied to the gaps 31c, 33b, 36a in a sufficiently cooled state, not after cooling (raising the temperature) 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 thus 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, so that the flow resistance to the oil flowing through the gaps 31c, 33b, 36a can be reduced, thereby making it possible to cool the permanent magnets 101, 102, ... even more efficiently.

[0091] In this embodiment, as shown in FIG. 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 become hotter than the permanent magnets 104, 105 farther from the stator 90.

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

[0093] In addition, while the 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 separating 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 separating the first and second radial oil passages 61', 62' on the radially outer side 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 section faces 61b, 62b. Therefore, in cases where the first section faces 61a, 62a and the second section faces 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 in the circumferential direction.

[0095] Fig. 15 is a perspective view 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 parts of the gaps 31c, 33b, 36a, in other words, communicate with the parts of the gaps 31c, 33b, 36a where oil does not collect, so that oil can be smoothly introduced from the first and second radial oil passages 61', 62' to the gaps 31c, 33b, 36a.

[0096] 13(b) and (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 the oil flowing 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 under centrifugal force. As a result, the permanent magnets 101, 102, 103, 106, which are one of the objects to be cooled, can be cooled more efficiently.

[0097] In this manner, the oil flow as shown in Figure 13(d) is realized, in other words, the portion 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 output shaft side> 1, 3 and 4, the end plates attached to the end portion of the output shaft side OS of the 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 concentrically to the axis of the rotor core at the end portion on the other axial side 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 aluminum plates that have the same outer shapes as the outer and inner circumferential surfaces of the rotor core 30 and 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 to overlap, when viewed 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] <4th 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 (c). Fig. 16(c) is a diagram showing the surface (rear surface 70b) of the OS on the output shaft side. Fig. 16(b) shows the thickness of the fourth end plate 70 exaggerated in comparison with its diameter to make the drawing easier to see.

[0101] As shown in Figures 16(a) to (c), the fourth end plate 70 is formed with eight outer through holes 71 that penetrate the fourth end plate 70 at equal intervals of 45 degrees in the circumferential direction. The radial positions of these outer through holes 71 correspond to the eight gaps 31c. In addition, the fourth end plate 70 is formed with sixteen inner through holes 73 that penetrate the fourth end plate 70 radially inward of the outer through holes 71 and have a larger diameter than the outer through holes 71. The radial positions of these inner through holes 73 correspond to the sixteen gaps 33b, 36a.

[0102] As shown in Fig. 16(a), eight U-shaped discharge recesses 79, whose outer periphery is recessed toward the output shaft side OS, are formed on the front surface 70a of the fourth end plate 70 at equal intervals of 45 degrees in the circumferential direction. Meanwhile, as shown in Fig. 16(c), communication grooves 75, 77, which are 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 showing a schematic diagram of the fifth end plate 80. Fig. 17(a) is a diagram showing the surface (front surface 80a) of the AOS on the side opposite the output shaft. Fig. 17(b) is a perspective view showing second diffusion grooves 81, 83. Note that the surface (rear 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, extending radially outward at equal intervals of 45 degrees in the circumferential direction and recessed into the output shaft side OS. The second short diffusion grooves 81 have radially inner ends that substantially coincide with the outer through holes 71, and extend to the outer peripheral surface 80c of the fifth end plate 80 and open at the outer peripheral surface 80c. The second short diffusion grooves 81 are formed so that their groove width increases radially outward.

[0105] Further, 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 in the radial direction, 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 substantially coincide with the inner through holes 73, and extend to the outer peripheral surface 80c of the fifth end plate 80 and open at the outer peripheral surface 80c. Like 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 passage> 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 a space formed by stacking the fourth and fifth end plates 70, 80 together. FIG. 18(c) and (d) are cross-sectional views showing the fourth and fifth end plates 70, 80 attached to the rotor core 30, which correspond to the cross-sectional views of the arrows taken along the lines cc and dd in FIG. 18(a), respectively. FIG. 18(e) is a perspective view showing the flow of oil in the rotor core 30 and the fourth and fifth end plates 70, 80. In FIG. 18(c) and (d), the thicknesses of the fourth and fifth end plates 70, 80 are exaggerated compared to their diameters in order to make the drawings easier to see.

[0107] As shown in Fig. 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 Fig. 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, the 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 the cross-sectional area increases as it goes radially outward.

[0108] Similarly, the second long diffusion grooves 83 are covered by the back surface 70b of the fourth end plate 70, 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, the radially inner end of each second long diffusion oil passage 83' communicates with the inner through-hole 73 and opens at the outer circumferential surface 80c of the fifth end plate 80, and is formed so that the cross-sectional area increases radially outward.

[0109] When the surface 70a of the fourth end plate 70 is attached to the end face 30b of the output shaft side OS of the rotor core 30 by welding or the like 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 showing the outer and inner through holes 71, 73. Meanwhile, since the oil flows in the axial direction through the gaps 31c, 33b, 36a, and flows radially outward through the second short diffusion oil passage 81' and the second long diffusion oil passage 83', it is assumed that the oil may not change direction smoothly. Therefore, in the rotor structure of this embodiment, the communication grooves 75, 77 having an R shape when viewed in the circumferential direction are formed at the portions where the second short diffusion oil passage 81' and the second long diffusion oil passage 83' communicate with the outer and inner through holes 71, 73. This allows the oil to be smoothly introduced from the gaps 31c, 33b, 36a to the second short diffusion oil passage 81' and the second long diffusion oil passage 83'.

[0111] By forming such second short diffusion oil passage 81' and second long diffusion oil passage 83', it becomes possible for the oil that has flowed through the gaps 31c, 33b, 36a to be scattered radially outward from the outer circumferential surface 80c of the fifth end plate 80 by centrifugal force through the second short diffusion oil passage 81' and the second long diffusion oil passage 83'. In this way, since the fourth and fifth end plates 70, 80 are arranged so as to overlap the coil end 93b of the output shaft side OS when viewed in the radial direction, it is possible to cool the coil end 93b of the output shaft side OS, which is one of the parts to be cooled.

[0112] Also, like the first diffusion oil passage 41, the second short diffusion oil passage 81' and the second long diffusion oil passage 83' are formed so that their cross-sectional areas increase radially outward, so that the second short diffusion oil passage 81' and the second long diffusion oil passage 83' can be prevented from being blocked by oil. This makes it possible to prevent a phenomenon in which the even distribution of oil is impaired due to an increase in the amount of oil flowing through the magnet holes communicating with the second short diffusion oil passage 81' and the second long diffusion oil passage 83' where negative pressure is generated.

[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, so that the coil end 93b can also be cooled efficiently.

[0114] In this manner, the oil flow as shown in Figure 18(e) is realized, in other words, the portion 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 between the third end plate 60 and the fourth end plate 70 in the axial direction, but because the rotor core 30 is a laminate of stacked magnetic thin plates, it is possible that oil flowing in the axial direction 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, but in this embodiment, the discharge recesses 69, 79 are formed in the third and fourth end plates 60, 70, so that oil that has leaked into the gaps between the magnetic thin plates can be discharged to the outside of the rotor core 30 through the discharge recesses 69, 79.

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

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

[0118] In addition, 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" communicating with the chamber space 43 may be provided, and oil may be caused to flow also into the gaps 34a, 35a as shown by the blackened areas in FIG. 20(b) to target the permanent magnets 104, 105. In addition, as shown by the blackened areas in FIG. 20(c), oil may be caused to flow also into the gaps 31a, 31e, 37a that are not in contact with the permanent magnets 101, 102, 103, 104, 105, 106 to indirectly cool the permanent magnets 103, 106.

[0119] Furthermore, in the above embodiment, the rotor core 30 is so-called skewless. However, this is not limited to the above. 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 sixteen, but this is not limited to the above 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 the number of magnetic poles 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 straight line, for example.

[0123] Furthermore, in the above embodiment, the end plates of the anti-output shaft side AOS are made up of the first to third end plates 40, 50, 60, and the end plates of the output shaft side OS are made up of the fourth and fifth end plates 70, 80. However, without being limited to this, the end plates of the anti-output shaft side AOS and the output shaft side OS may each be made from a single member, for example, using a sand mold for casting.

[0124] As such, the above-described embodiment is merely illustrative in all respects and should not be interpreted as being limiting. Furthermore, all modifications and variations 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 beneficial when applied to the rotor structure of a synchronous motor. [Explanation of symbols]

[0126] 1 Synchronous motor 10 Rotor 20 rotor shaft 30 Rotor core 31, 33, 36 Magnet hole 40 First end plate (one side end plate) 41 First diffusion oil passage 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 partitioning the radial oil passage on one side in 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 (part to be cooled) 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 a rotor rotates in synchronization with a rotating magnetic field generated by a stator, The rotor includes a plurality of permanent magnets which are one of the cooling targets, a cylindrical rotor core in which a plurality of magnet holes extending in the axial direction are formed and in which the permanent magnets are embedded, a rotor shaft which is inserted into the rotor core so as not to rotate relative to the rotor shaft, and an annular one-side end plate which is attached to one end of the rotor core in the axial direction and concentric with the axis of the rotor core, In the one end plate, a chamber space having an annular shape when viewed in the axial direction is formed concentrically with the axis of the rotor core, and a plurality of connecting flow paths extending radially on the radially inner side of the chamber space and communicating with an oil path in the rotor shaft and the chamber space, and a plurality of radial oil paths extending radially and communicating with the chamber space and the plurality of magnet holes are formed so as to be offset from each other in the circumferential and axial directions, A rotor structure characterized in that oil is filled into the chamber space from the oil passage in the rotor shaft through the multiple connecting flow paths, and oil distributed from the chamber space through the multiple radial oil passages passes through the multiple magnet holes and flows axially inside the rotor core.

2. In the rotor structure according to claim 1, the plurality of radial oil passages extend radially on the other axial side of the chamber space, and are formed in the one-side end plate such that radially inner ends communicate with the chamber space and radially outer ends communicate 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 in the circumferential direction.

3. In the rotor structure according to claim 1, the plurality of radial oil passages extend radially on the other axial side of the chamber space, and are formed in the one-side end plate such that radially inner ends communicate with the chamber space and radially outer ends communicate 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 a radially inner portion of each of the magnet holes.

4. In the rotor structure according to claim 1, the one-side end plate is disposed so as to overlap, as viewed in a radial direction, a coil end on one axial side, which is one of the cooling targets, of a stator coil attached to the stator, 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, the radially inner ends of the first diffusion oil passages communicating with the chamber space, and opening on 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 its cross-sectional area increases toward the radially outer side.

5. In the rotor structure according to claim 4, 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 a 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 has a plurality of second diffusion oil passages extending radially, each of which has a radially inner end communicating with the plurality of magnet holes, and which open on the outer peripheral surface of the other end plate and has a cross-sectional area that increases 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.

6. In the rotor structure according to claim 1, A rotor structure in which the rotor core has a skew angle of 0 degrees.

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