Cooling structure for rotating electrical machinery

Abstract

This invention provides a cooling structure for a rotating electric machine that allows for cooling of the inside of permanent magnets and coil ends with a simple configuration, even when it is difficult to form oil passages in the rotating body. [Solution] This is a cooling structure for a rotating electric machine comprising a rotor 10 having a cylindrical rotor core in which permanent magnets 13 are embedded, and a stator 20 to which stator coils are mounted. It further comprises a first end plate 15 attached to the axial end of the rotor core so as to overlap the coil ends of the stator coils in the radial direction, and an oil supply means capable of dripping oil onto the outer circumferential surface of the first end plate 15. A recess 16 is formed on the outer circumferential surface of the first end plate 15, with the portion on the rotor core side in the axial direction being radially recessed. The recess 16 is formed in a position and shape that exposes the axial end of the permanent magnet 13.

Description

Technical Field

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[0003]

[0001] The present invention relates to a cooling structure for a rotating electric machine.

Background Art

[0002] For motors used in electric vehicles, hybrid vehicles, etc., improvements in mounting performance and productivity, facilitation of vehicle model expansion, and cost reduction are desired. To achieve these, miniaturization of the motor while maintaining the output, in other words, increasing the output density of the motor, is required.

[0003] In increasing the output density of a motor, it is inevitable to increase the density of the current flowing through the stator coil. However, when increasing the current density in a synchronous motor, the heat generation amount of the permanent magnet increases, and the temperature of each part inside the motor rises. Therefore, in some cases, there is a possibility of demagnetization of the permanent magnet and, consequently, a decrease in motor torque. For this reason, various structures for cooling the permanent magnet inside the rotor core and the radially inner side of the coil end of the stator coil, where it is relatively difficult to supply refrigerant, have been proposed conventionally.

[0004] For example, in Patent Document 1, refrigerant supplied from a refrigerant flow path provided inside a rotor shaft is supplied to a refrigerant flow path hole disposed near a magnetic pole portion through a refrigerant introduction groove formed in an end plate by the centrifugal force acting on the refrigerant to cool the magnet, and the coil end is cooled by discharging it from a refrigerant discharge hole formed in the end plate. A rotating electric machine is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional cooling structures, such as the one described in Patent Document 1 above, often supply cooling oil to the vicinity of permanent magnets or coil ends by injecting oil (refrigerant) from a rotating body such as a rotor shaft. However, in hybrid vehicles, for example, where the engine and motor are directly connected on the same shaft, the motor is sandwiched axially (in the direction in which the rotor shaft extends) between the engine and the transmission, etc., making it difficult to form oil passages to the rotating body due to design constraints such as space.

[0007] The present invention has been made in view of the above, and its objective is to provide a cooling structure for a rotating electric machine that can cool the radially inner side of the permanent magnets and coil ends in the rotor with a simple configuration, even when it is difficult to form oil passages in the rotating body. [Means for solving the problem]

[0008] To achieve the above objective, the cooling structure for a rotating electric machine according to the present invention is provided with a recess on the outer circumferential surface of the end plate so as to expose the axial end of the permanent magnet, and by dripping oil onto the outer circumferential surface of the end plate, the permanent magnet is cooled by the oil accumulated in the recess, and the radially inner side of the coil end is also cooled by the oil that bounces back as it hits the recess of the rotating end plate.

[0009] Specifically, the present invention relates to a cooling structure for a rotating electric machine comprising a rotor having a cylindrical rotor core in which axially extending permanent magnets are embedded, and a stator having stator coils mounted on it, which is arranged radially outward from the rotor core.

[0010] And the cooling structure of this rotating electric machine is ,before The rotor core is further provided with an end plate attached to the axial end of the rotor core, and an oil supply means on the outer circumferential surface of the end plate from which oil can be dripped, wherein the outer circumferential surface of the end plate has a recess in the radial direction on the rotor core side in the axial direction , the coil end of the stator coil, and overlapping in the radial directionThe recess is formed in such a position and shape that it exposes the axial end of the permanent magnet.

[0011] In this configuration, the outer surface of the end plate has a recess formed in the radial direction on the rotor core side in the axial direction, so that oil dripped onto the outer surface of the end plate by the oil supply means accumulates in the recess. Here, the recess is formed in a position and shape that exposes the axial end of the permanent magnet, so that the permanent magnet (or its end) can be cooled by the oil accumulated in the recess.

[0012] Furthermore, the oil dripped onto the outer surface of the end plate by the oil supply means is bounced off by the irregularities (concavees) on the outer surface of the rotating end plate. As a result, this bounced-off oil is supplied to the radially inward side of the coil end. This allows for cooling of the radially inward side of the upper coil end, which is relatively difficult to supply with refrigerant, unlike the lower coil end where the dripped oil is supplied.

[0013] As described above, according to the present invention, even when it is difficult to form oil passages in the rotating body, the radially inner side of the permanent magnets and coil ends in the rotor can be cooled with a simple configuration of forming recesses on the outer circumferential surface of the end plate.

[0014] Furthermore, in the cooling structure for the rotating electric machine described above, the recess may be formed such that at least the axial end of the permanent magnets, which are arranged radially outward from the rotor core, is exposed.

[0015] For example, forming deep radial recesses on the outer surface of the end plate may increase the rotor's rotational resistance. However, with this configuration, the recesses are formed in such a way that they expose the axial ends of the permanent magnets located on the radially outer side, which are the most prone to temperature increases. In other words, relatively shallow recesses are formed, which allows for effective cooling of the radially outer permanent magnets (and their ends), which are the most prone to temperature increases, while suppressing an increase in the rotor's rotational resistance.

[0016] Furthermore, in the cooling structure of the rotating electric machine described above, the recess may be formed in the shape of a groove extending in the circumferential direction of the end plate.

[0017] With this configuration, by forming groove-shaped recesses that extend circumferentially on the end plate, oil can accumulate more easily in the recesses compared to when the recesses are shorter circumferentially, thus allowing for more reliable cooling of the permanent magnets (or their ends).

[0018] Furthermore, in the cooling structure of the rotating electric machine described above, the recesses may be provided in multiple locations at equal intervals in the circumferential direction of the end plate.

[0019] This configuration allows for effective cooling of the permanent magnets (or their ends) while suppressing an increase in the rotor's rotational resistance by providing multiple recesses at equal intervals around the end plate. [Effects of the Invention]

[0020] As described above, the cooling structure for a rotating electric machine according to the present invention allows for cooling of the radially inner side of the permanent magnets and coil ends in the rotor with a simple configuration, even when it is difficult to form oil passages in the rotating body. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic perspective view showing a motor according to an embodiment of the present invention. [Figure 2] This is a schematic longitudinal cross-sectional view showing the main components of the motor. [Figure 3] It is a diagram schematically showing a rotor core and a stator. [Figure 4] It is a perspective view schematically showing a state where a cooling block is arranged on the radially inner side of a rotor. [Figure 5] It is a diagram schematically explaining the flow of oil in a motor. [Figure 6] It is an end face view in the arrow direction of the third plate corresponding to the line VI-VI in FIG. 5. [Figure 7] It is a cross-sectional view in the arrow direction of the fourth plate corresponding to the line VII-VII in FIG. 5. [Figure 8] It is a perspective view schematically explaining the flow of oil dripping from the second through-hole group to the outer peripheral surface of the first end plate. [Figure 9] It is a diagram schematically showing a recess according to another embodiment.

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments for carrying out the present invention will be described based on the drawings.

[0023] -Overall Configuration of Motor- FIG. 1 is a perspective view schematically showing a motor 1 according to the present embodiment, and FIG. 2 is a longitudinal sectional view schematically showing a main part of the motor 1. In the following description, for convenience, as shown in FIGS. 1 and 2, one side in the axial direction (the left side in FIG. 2, the direction in which the rotor shaft 3 extends) is referred to as "one side ON", and the other side in the axial direction (the right side in FIG. 2) is referred to as "the other side OT". Also, the arrow U in FIGS. 1 and 2 indicates the upper side, and the arrow D indicates the lower side, respectively. In FIG. 2, a part of the stator coil 23 and the housing 50 are omitted from illustration. Also, in FIG. 2, for easy viewing of the figure, the hatching representing the cross section is omitted.

[0024] This motor (rotating electric machine) 1 is, for example, mounted as a drive source together with an engine (not shown) in a so-called plug-in hybrid electric vehicle (PHEV (Plug-in Hybrid Electric Vehicle)) that can charge a battery (not shown) by an external power source. While the motor 1 functions as an electric motor that rotates using power supplied from the battery, it also functions as a generator capable of regenerative power generation when the vehicle is decelerating, for example.

[0025] As described later, this motor 1 is miniaturized by adopting a so-called T-type rotor structure, and as shown in Figures 1 and 2, it comprises a rotor shaft 3, a rotor 10, a stator 20, a cooling block 30, a motor cover 40, a housing 50, and first and second oil supply units 71 and 72 connected to an oil pump (not shown), which is the source of the oil supply.

[0026] -Rotor- The rotor 10 has a cylindrical rotor core 11, a plurality of permanent magnets 13, first and second end plates 15 and 17, and a rotor inner cylinder portion 19 that connects the rotor core 11 and the rotor shaft 3, and is cylindrical in shape overall.

[0027] <Rotor core and permanent magnet> Figure 3 is a schematic diagram showing the rotor core 11 and stator 20. In Figure 3, the permanent magnets 13 are hatched for clarity. The rotor core 11 is formed into a cylindrical shape by stacking a predetermined number of annular magnetic thin plates in the axial direction. As shown in Figure 3, the rotor core 11 has multiple axially extending magnet holes 11a for inserting axially extending permanent magnets 13. By inserting (embedding) multiple permanent magnets 13 into each of these multiple magnet holes 11a, 12 magnetic poles composed of permanent magnets 13 are formed. The parts of the magnet holes 11a that are not filled with permanent magnets 13 remain as voids (flux barriers).

[0028] <End Plate> The first end plate 15 and the second end plate 17 are formed in an annular shape and, as shown in Figure 2, are attached to both ends of the cylindrical rotor core 11 in the axial direction to prevent the permanent magnets 13 from protruding from the ends of the rotor core 11. More specifically, the first end plate 15 is attached to one end of the rotor core 11 (ON), while the second end plate 17 is attached to the other end of the rotor core 11 (OT).

[0029] The first end plate 15 is formed by stacking the first plate 61, the second plate 62, and the third plate 63, each formed in an annular shape, in the order from one axial side ON to the other axial side OT. The second end plate 17 is formed by stacking the fourth plate 64 and the fifth plate 65, each formed in an annular shape, in the order from one axial side ON to the other axial side OT.

[0030] <Rotor inner cylinder section> As shown in Figure 2, the rotor inner cylinder portion 19 has an outer cylinder portion 19a attached to the inner circumferential surface of the rotor core 11, an inner cylinder portion 19b attached to the outer circumferential surface of the rotor shaft 3, and an annular plate-shaped connecting portion 19c that connects the outer cylinder portion 19a and the inner cylinder portion 19b at the axial center, and is formed in a cylindrical shape overall. The rotor inner cylinder portion 19 configured in this way is positioned radially inward of the rotor core 11 and connects the inner circumferential surface of the rotor core 11 and the outer circumferential surface of the rotor shaft 3 via the connecting portion 19c. In the outer cylinder portion 19a of the rotor inner cylinder portion 19, an oil introduction hole 19d is formed through the outer cylinder portion 19a in the radial direction, in the portion corresponding to the third plate 63 (axial position).

[0031] In this way, by adopting a so-called T-type rotor structure that connects the inner circumferential surface of the rotor core 11 and the outer circumferential surface of the rotor shaft 3 via a relatively thin, annular plate-shaped connecting portion 19c, spaces S1 and S2 are formed radially inward of the rotor core 11, as shown in Figure 2. By arranging components such as a transmission in these spaces S1 and S2, it becomes possible to miniaturize the motor 1 while increasing the space for arranging peripheral components.

[0032] -Stator- The stator 20 is located radially outside the rotor core 11 and, as shown in Figures 2 and 3, has a cylindrical stator core 21 and stator coils 23 mounted on the stator core 21. The stator core 21 is constructed, for example, by stacking multiple electromagnetic steel plates in the axial direction, and has multiple slots 22 (see Figure 8) that open radially inward. The stator coils 23 are mounted on the stator core 21 so as to be housed in the slots 22. The portion of the stator coil 23 protruding from one side ON from the slot 22 constitutes the first coil end 23a, and the portion protruding from the other side OT from the slot 22 constitutes the second coil end 23b. The first coil end 23a overlaps with the first end plate 15 when viewed radially, while the second coil end 23b overlaps with the second end plate 17 when viewed radially.

[0033] -Motor cover- As shown in Figures 1 and 2, the motor cover 40 is formed in a cylindrical shape. The motor cover 40 is positioned radially outside the stator core 21 and covers the rotor shaft 3, rotor 10, and stator 20 from the radial outside. As shown in Figure 2, the motor cover 40 has an arc-shaped shell cover 41 positioned radially outside the motor cover 40 such that, when viewed from above, it overlaps with the stator core 21 and the first and second coil ends 23a, 23b, and an arc-shaped space 43 is formed between it and the outer surface of the motor cover 40. The shell cover 41 is provided with an oil inlet 45 for introducing oil into the arc-shaped space 43.

[0034] In the portion of the motor cover 40 that overlaps with the shell cover 41, there are multiple groups of through-holes, a first through-hole group 40a, a second through-hole group 40b, and a third through-hole group 40c (see Figure 5), each consisting of multiple through-holes that penetrate the motor cover 40 radially and are arranged circumferentially. These groups are formed at axial intervals to supply oil to different cooling targets within the motor cover 40 (for example, the stator core 21 and the first and second coil ends 23a, 23b). As a result, when oil is supplied from the second oil supply unit 72 into the space 43 via the oil inlet 45, the oil is showered onto the stator core 21 and the first and second coil ends 23a, 23b from the radially outside via the first to third through-hole groups 40a, 40b, and 40c, which are composed of multiple through-holes arranged circumferentially.

[0035] -housing- As shown in Figure 1, the housing 50 is bell-shaped when viewed from the axial direction and includes a housing body 51 that houses the rotor 10, stator 20, etc., a first housing cover 53 that covers the opening of the housing body 51 from one axial side ON, and a second housing cover 55 that covers the opening of the housing body 51 from the other axial side OT. The second oil supply unit 72 is provided on the upper side of the housing body 51, while the first oil supply unit 71 is provided on the first housing cover 53.

[0036] In the cooling structure of the rotating electric machine according to this embodiment, oil that has absorbed the heat generated by the rotor 10, stator 20, etc., accumulates at the bottom of the housing 50, is then sucked into an oil pump, cooled by a heat exchanger (not shown), and then supplied again to the rotor 10, stator 20, etc., via the first and second oil supply units 71 and 72.

[0037] -Cooling Block- Figure 4 is a schematic perspective view showing the cooling block 30 positioned radially inward of the rotor 10, and Figure 5 is a schematic diagram illustrating the oil flow in the motor 1. Note that the housing 50 is omitted from the illustrations in Figures 4 and 5, and only the upper half of the motor 1 is shown in Figure 5. Furthermore, Figure 5 is merely a general illustration of the oil flow, and for the sake of clarity, the size and circumferential position of each component are not necessarily accurate.

[0038] By the way, when miniaturizing the motor 1 as in this embodiment, maintaining the output of the motor 1 requires increasing the power density of the motor 1. In order to increase the power density of the motor 1, it is unavoidable to increase the current density flowing through the stator coil 23. However, increasing the current density in a synchronous motor increases the amount of heat generated by the permanent magnet 13, which raises the temperature of various parts inside the motor 1. In some cases, this may lead to demagnetization of the permanent magnet 13 and, consequently, a decrease in motor torque.

[0039] Therefore, it is conceivable to cool the permanent magnets 13 inside the rotor core 11 and the first and second coil ends 23a and 23b of the stator coil 23, through which a high-density current flows, with oil. However, in hybrid vehicles, for example, where the engine and motor are directly connected on the same axis, the motor is sandwiched axially between the engine and the transmission, etc., making it difficult to form an oil passage within the rotor shaft, or in other words, difficult to supply oil from the rotor shaft to the rotor. In this embodiment as well, due to the spatial design constraint of the presence of other devices (not shown) on one axial side ON of the motor 1, it is difficult to supply oil from the rotor shaft 3 as shown by the dashed arrow in Figure 2 (see the × mark in Figure 2). Therefore, compared to a structure that ejects oil radially outward from the rotor shaft 3 by centrifugal force, it is relatively difficult to supply coolant to the radially inward side of the permanent magnets 13 inside the rotor core 11 and the first and second coil ends 23a and 23b of the stator coil 23.

[0040] Therefore, in the cooling structure of the rotating electric machine (motor 1) according to this embodiment, oil supplied to the inner circumferential surface of the rotor 10 from a cooling block 30, which is a non-rotating body located radially inside the cylindrical rotor 10, is supplied to the permanent magnet 13 by utilizing the negative pressure generated by the rotation of the rotor 10.

[0041] The cooling block 30 is a non-rotating body pre-fixed to the first housing cover 53, and as shown in Figure 4, it has an annular block body portion 31, an annular ring portion 33 arranged radially outside the block body portion 31, a plurality of connecting portions 35 that connect the outer circumferential surface of the block body portion 31 and the inner circumferential surface of the ring portion 33, and an oil inlet 37.

[0042] As shown in Figure 5, an annular space is formed inside the annular block body 31, which serves as an oil space 32 to which oil is supplied. Multiple ejection holes 39 are formed in the annular ring portion 33 at equal intervals in the circumferential direction, penetrating the ring portion 33 radially. Multiple connecting portions 35 extend radially at circumferential positions corresponding to the ejection holes 39. An oil passage 36 is formed inside each connecting portion 35, connecting the oil space 32 and the ejection holes 39. An oil inlet 37 is provided in the block body 31 and is connected to the first oil supply unit 71.

[0043] As shown in Figures 2 and 5, the cooling block 30 is positioned radially inward of the rotor 10 so as to overlap radially with the first coil end 23a of the stator coil 23 (which is ON on one side in the axial direction) and the first end plate 15 of the rotor 10.

[0044] Furthermore, as shown in Figures 2, 4, and 5, the cooling block 30 is positioned radially inward of the rotor 10 with the outer surface of the ring portion 33 close to the inner surface of the outer cylindrical portion 19a, such that an air gap G is formed between the outer surface of the ring portion 33 and the inner surface of the outer cylindrical portion 19a of the rotor inner cylindrical portion 19. At this time, the rotor shaft 3 is inserted radially inward of the annular block body portion 31.

[0045] With the above configuration, when oil is supplied from the first oil supply unit 71 to the oil space 32 via the oil inlet 37, the supplied oil accumulates evenly in the annular oil space 32. The oil accumulated evenly in the oil space 32 is supplied through the oil passage 36 formed inside the connecting unit 35 to the air gap G between the outer surface of the ring unit 33 and the inner surface of the rotor inner cylinder 19 through the multiple ejection holes 39 formed in the ring unit 33. This realizes the oil flow shown by the thick arrow OFA in Figure 5.

[0046] -Oil flow in the rotor- The first end plate 15, by combining grooves and through holes formed in the first plate 61, the second plate 62, and the third plate 63, forms a rotor internal oil passage 15a, as shown in Figure 5. This passage extends radially outward from its inner circumferential surface at an axial position corresponding to the oil introduction hole 19d of the rotor inner cylinder portion 19, and communicates with the magnet hole 11a (more precisely, the void) into which the permanent magnet 13 is inserted.

[0047] As the rotor 10 is rotating, a negative pressure is generated in the rotor's internal oil passage 15a, which has a radially extending portion, due to the centrifugal force accompanying the rotation of the rotor 10, which draws the fluid radially outward. As a result, the oil supplied to the air gap G is drawn into the oil inlet hole 19d of the rotor's internal cylinder 19 and supplied to the magnet hole 11a via the rotor's internal oil passage 15a. This enables the oil supplied from the non-rotating cooling block 30 to create the oil flow shown by the thick arrows OFB and OFC in Figure 5, thereby directly cooling the permanent magnet 13.

[0048] Furthermore, the first end plate 15 has multiple first diffusion oil passages 15b formed therein, the radially inner end of which communicates with the rotor internal oil passage 15a, and which extend radially outward and open on the outer circumferential surface of the rotor 10. Since the first coil end 23a overlaps with the first end plate 15 when viewed radially, a portion of the oil in the rotor internal oil passage 15a flows into the first diffusion oil passages 15b, and is diffused radially outward by the centrifugal force accompanying the rotation of the rotor 10, and supplied to the first coil end 23a from the radially inner side. As a result, the oil supplied from the non-rotating cooling block 30 realizes the oil flow shown by the thick arrow OFD in Figure 5, making it possible to cool the radially inner side of the first coil end 23a as well.

[0049] Furthermore, the second end plate 17 has multiple second diffusion oil passages 17a formed therein, the radially inner end of which communicates with the magnet hole 11a, and which extend radially outward and open on the outer circumferential surface of the rotor 10. Since the second coil end 23b overlaps with the second end plate 17 when viewed radially, the oil that flows through the magnet hole 11a from one axial side ON to the other side OT while cooling the permanent magnet 13 flows into the second diffusion oil passages 17a, and is diffused radially outward by the centrifugal force accompanying the rotation of the rotor 10, and supplied to the second coil end 23b from the radially inner side. As a result, the oil supplied from the non-rotating cooling block 30 realizes the oil flow shown by the thick arrow OFE in Figure 5, making it possible to cool the radially inner side of the second coil end 23b as well.

[0050] -Oil flow in the stator- As described above, the motor cover 40 is configured such that an arc-shaped shell cover 41 is positioned radially outward from the motor cover 40, forming an arc-shaped space 43 between the outer surface of the motor cover 40 and the shell cover 41. Oil is supplied from the second oil supply unit 72 into the space 43 via the oil inlet 45. This achieves the oil flow shown by the thick arrows OFF and OFG in Figure 5.

[0051] As shown in Figure 5, in the portion of the motor cover 40 that overlaps with the shell cover 41, a first group of through-holes 40a is formed, each of which penetrates the motor cover 40 radially and is arranged circumferentially. This group of through-holes is formed so as to overlap with the central part of the stator core 21 when viewed radially. In addition, the stator core 21 has stator internal oil passages 21a that extend radially inward at the axial center and extend on both axial sides. As a result, oil from the space 43 is supplied from the radial outside through the first group of through-holes 40a to the stator internal oil passages 21a of the stator core 21, realizing an oil flow that directly cools the stator core 21, as shown by the thick arrow OFH in Figure 5.

[0052] Furthermore, in the portion of the motor cover 40 that overlaps with the shell cover 41, as shown in Figure 5, a third group of through-holes 40c is formed, consisting of multiple through-holes that penetrate the motor cover 40 radially and are arranged circumferentially, so as to overlap the first and second coil ends 23a and 23b when viewed radially. As a result, oil from the space 43 is supplied to the first and second coil ends 23a and 23b through the third group of through-holes 40c, realizing an oil flow that cools the first and second coil ends 23a and 23b from the radially outside, as indicated by the thick arrow OFI in Figure 5.

[0053] In addition, as shown in Figure 5, in the portion of the motor cover 40 that overlaps with the shell cover 41, a second group of through-holes 40b is formed, consisting of multiple through-holes that penetrate the motor cover 40 radially and are arranged circumferentially, so as to overlap with the first and second end plates 15 and 17 when viewed radially. As a result, oil from the space 43 is supplied to the first and second end plates 15 and 17 through the second group of through-holes 40b, realizing an oil flow as shown by the thick arrow OFJ in Figure 5. Therefore, in relation to the claims, the second oil supply unit 72, oil inlet 45, space 43, and second group of through-holes 40b in this embodiment correspond to the "oil supply means capable of dripping oil onto the outer circumferential surface of the end plate" as defined in the present invention.

[0054] -First and second end plates- In this embodiment, as described above, the permanent magnet 13 can be directly cooled by the oil flow shown by the thick arrow OFC in Figure 5. However, in order to further cool the permanent magnet 13, it is preferable to supply more oil to the permanent magnet 13. In particular, the permanent magnet 13 located radially outward in the rotor core 11 tends to become hotter than the permanent magnet 13 located radially inward, so it is preferable to supply more oil to the radially outward permanent magnet 13.

[0055] Furthermore, the radially inner surface of the first coil end 23a can be cooled by the oil flow indicated by the thick arrow OFD in Figure 5, and the radially inner surface of the second coil end 23b can be cooled by the oil flow indicated by the thick arrow OFE in Figure 5. However, in order to further cool the first and second coil ends 23a and 23b, it is preferable to supply more oil to the first and second coil ends 23a and 23b. In particular, unlike the first and second coil ends 23a and 23b located below to which dripped oil is supplied, it is difficult to supply oil to the radially inner surface of the first and second coil ends 23a and 23b located above, so it is preferable to supply more oil to the first and second coil ends 23a and 23b located above from the radially inner surface.

[0056] Therefore, in the cooling structure of the rotating electric machine according to this embodiment, recesses are provided on the outer circumferential surfaces of the first and second end plates 15 and 17 so as to expose the axial ends of the permanent magnets 13. By dripping oil onto the outer circumferential surfaces of the first and second end plates 15 and 17, the permanent magnets 13 are cooled by the oil accumulated in the recesses, and the radially inner surfaces of the first and second coil ends 23a and 23b are also cooled by the oil that bounces back as it hits the recesses on the outer circumferential surfaces of the rotating first and second end plates 15 and 17.

[0057] Figure 6 is an end view of the third plate 63 as seen through the arrow, corresponding to the line VI-VI in Figure 5. In Figure 6, reference numerals 63a, 63b, and 63c indicate the chamber space 63a, which forms the rotor internal oil passage 15a and is annular in shape when viewed in the axial direction; the connecting oil passage 63b, which extends radially outward from the inner circumferential surface of the third plate 63 and communicates with the radially inner side of the chamber space 63a; and the through hole 63c, which penetrates the third plate 63 axially at a circumferential distance within the chamber space 63a and communicates with the magnet hole 11a, respectively.

[0058] As shown in Figure 6, a radially recessed notch 16' is formed on the outer circumferential surface of the third plate 63. Although not shown, a radially recessed notch 16' is also formed on the outer circumferential surface of the second plate 62, similar to the third plate 63. Therefore, by overlapping the second plate 62 and the third plate 63 in the axial direction so that the notches 16' coincide, and sandwiching these second and third plates 62 and 63 between the first plate 61 and the end face ON on one axial side of the rotor core 11, the notch 16' is covered, and a radially recessed recess 16 is formed on the outer circumferential surface of the first end plate 15, on the rotor core 11 side (the other side OT) in the axial direction.

[0059] As shown in Figure 6, the recesses 16 formed in this manner are positioned and shaped (depth) such that at least the axial ends of the permanent magnets 13 located radially outward from the rotor core 11 are exposed. In addition, multiple recesses 16 are provided at equal intervals in the circumferential direction of the first end plate 15 in order to suppress an increase in the rotational resistance of the rotor 10. Furthermore, each recess 16 is formed in the shape of a groove extending in the circumferential direction of the first end plate 15 so that oil can easily accumulate.

[0060] Each recess 16 has a bottom surface 16a extending in the circumferential direction, and side surfaces 16b connecting both circumferential ends of the bottom surface 16a to the outer circumferential surface of the third plate 63 (first end plate 15), as shown in the enlarged view of Figure 6. The bottom surface 16a is formed in an arc shape concentric with the first end plate 15 when viewed in the axial direction, in order to suppress an increase in the rotational resistance of the rotor 10. In addition, in order to suppress an increase in the rotational resistance of the rotor 10, the connection portion 16c between the outer circumferential surface of the third plate 63 (and the second plate 62) and the side surface 16b is chamfered with a radius of curvature R1, and the connection portion 16d between the bottom surface 16a and the side surface 16b is chamfered with a radius of curvature R2 (>R1).

[0061] Figure 7 is a cross-sectional view of the fourth plate 64, corresponding to the line VII-VII in Figure 5. In Figure 7, reference numeral 64a indicates a through hole 64a that penetrates the fourth plate 64 axially, at a position corresponding to the magnet hole 11a which constitutes the second diffusion oil passage 17a. As shown in Figure 7, a notch 18' is formed on the outer circumferential surface of the fourth plate 64, with the portion on the rotor core 11 side (one side ON) in the axial direction recessed radially. In other words, the fourth plate 64 has a notch 18' formed on its outer circumferential edge, with the surface on the rotor core 11 side (one side ON) recessed toward the opposite side of the rotor core 11 in the axial direction (the other side OT). Therefore, by overlapping the ON side of the fourth plate 64 with the OT end face of the rotor core 11, the notch 18' is covered, and a recess 18 is formed on the outer circumferential surface of the second end plate 17, with the portion on the rotor core 11 side (the ON side) in the axial direction being radially recessed.

[0062] As shown in Figure 7, the recesses 18 formed in this manner are positioned and shaped (depth) such that at least the axial ends of the permanent magnets 13 located radially outward from the rotor core 11 are exposed. In addition, multiple recesses 18 are provided at equal intervals in the circumferential direction of the second end plate 17 in order to suppress an increase in the rotational resistance of the rotor 10. Furthermore, each recess 18 is formed in the shape of a groove extending in the circumferential direction of the second end plate 17 so that oil can easily accumulate.

[0063] Each recess 18 has a bottom surface 18a extending in the circumferential direction, and side surfaces 18b connecting both circumferential ends of the bottom surface 18a to the outer circumferential surface of the fourth plate 64 (second end plate 17), as shown in the enlarged view of Figure 7. The bottom surface 18a is formed in an arc shape concentric with the second end plate 17 when viewed in the axial direction, in order to suppress an increase in the rotational resistance of the rotor 10. Furthermore, in order to suppress an increase in the rotational resistance of the rotor 10, the connection portion 18c between the outer circumferential surface of the fourth plate 64 and the side surface 18b is chamfered with a radius of curvature R1, and the connection portion 18d between the bottom surface 18a and the side surface 18b is chamfered with a radius of curvature R2 (>R1).

[0064] Figure 8 is a schematic perspective view illustrating the flow of oil dripping from the second through-hole group 40b onto the outer surface of the first end plate 15. In Figure 8, for the sake of clarity, the permanent magnet 13 is hatched, and the first coil end 23a, which protrudes from the slot 22 in one axial direction (ON), is omitted from the illustration.

[0065] With the above configuration, when oil is supplied to the first coil end 23a from the radially outer side via the second through-hole group 40b in a shower-like manner, the oil dripping through the gaps between the first coil ends 23a, as shown by the thick arrow A in Figure 8, accumulates in the recesses 16 of the grooves formed on the outer circumferential surface of the first end plate 15, as shown by the thick arrow B in Figure 8. As a result, the axial ON end of the permanent magnet 13, which is located radially outward and is particularly prone to becoming hot, is cooled by the oil accumulated in the recesses 16.

[0066] Furthermore, some of the oil dripping through the first coil ends 23a hits the irregularities (recesses 16) formed on the outer surface of the rotating first end plate 15, and is bounced radially outward as shown by the thick arrow C in Figure 8, and is supplied to the first coil ends 23a from the radially inward near the slot 22. As a result, the first coil ends 23a are cooled by the oil at a different location (near the slot 22) than where the oil diffused from the first diffusion oil passage 15b hits.

[0067] Although not shown in the diagram, similarly in the second end plate 17, when oil is supplied in a shower-like manner to the second coil end 23b from the radially outside through the second through-hole group 40b, a portion of the oil dripping through the second coil end 23b accumulates in the recesses 18 of the grooves formed on the outer circumferential surface of the second end plate 17, thereby cooling the other axial end OT of the permanent magnet 13 with the oil accumulated in the recesses 18. The remaining portion of the oil dripping through the second coil end 23b hits the irregularities (recesses 18) formed on the outer circumferential surface of the rotating second end plate 17, bounces radially outward, and is supplied to the second coil end 23b from the radially inside near the slot 22. As a result, the second coil end 23b is cooled by the oil at a different location (near the slot 22) than where the oil diffused from the second diffusion oil passage 17a hits.

[0068] -Effects- According to the cooling structure of the rotating electric machine according to this embodiment, recesses 16 and 18 are formed on the outer circumferential surfaces of the first and second end plates 15 and 17, with the portion facing the rotor core 11 in the axial direction being radially recessed. As a result, oil dripped from the second through-hole group 40b onto the outer circumferential surfaces of the first and second end plates 15 and 17 accumulates in the recesses 16 and 18. Here, since the recesses 16 and 18 are formed in a position and shape that exposes the axial end of the permanent magnet 13, the oil accumulated in the recesses 16 and 18 can cool the permanent magnet 13 (or its end).

[0069] Furthermore, the oil dripped from the second through-hole group 40b onto the outer circumferential surfaces of the first and second end plates 15 and 17 is repelled by the irregularities (recesses 16 and 18) on the outer circumferential surfaces of the rotating first and second end plates 15 and 17. As a result, this repelled oil is supplied to the radially inward side of the first and second coil ends 23a and 23b, which are located on the upper side where it is relatively difficult to supply coolant, thus enabling cooling of the radially inward side of the first and second coil ends 23a and 23b.

[0070] As described above, with this simple configuration of forming recesses 16 and 18 on the outer circumferential surfaces of the first and second end plates 15 and 17, it is possible to cool the radially inner sides of the permanent magnets 13 and the first and second coil ends 23a and 23b in the rotor 10, even when it is difficult to form oil passages in the rotor shaft 3.

[0071] In this embodiment, forming deep radial recesses on the outer surfaces of the first and second end plates 15 and 17 could increase the rotational resistance of the rotor 10. However, in this embodiment, recesses 16 and 18 are formed in such a way that the axial ends of the permanent magnets 13 located on the radially outer side, which are the most prone to temperature increases, are exposed. In other words, relatively shallow recesses 16 and 18 are formed, thereby effectively cooling the radially outer permanent magnets 13 (the ends) that are most prone to temperature increases, while suppressing an increase in the rotational resistance of the rotor 10.

[0072] Furthermore, by forming groove-shaped recesses 16 and 18 in the circumferential direction of the first and second end plates 15 and 17, oil is more likely to accumulate in the recesses 16 and 18, thereby enabling more reliable cooling of the permanent magnet 13 (or its end).

[0073] Furthermore, by providing multiple recesses 16 and 18 at equal intervals in the circumferential direction of the first and second end plates 15 and 17, it is possible to effectively cool the permanent magnets 13 (or their ends) while suppressing an increase in the rotational resistance of the rotor 10.

[0074] (Other embodiments) The present invention is not limited to its embodiments and can be implemented in various other ways without departing from its spirit or main features.

[0075] In the above embodiment, the present invention is applied to a motor 1 equipped with a cooling block 30 and a shell cover 41. However, the present invention is not limited to this, and may also be applied to a motor 1 without a cooling block 30 and / or a shell cover 41, as long as recesses 16 and 18 are formed on the outer circumferential surfaces of the first and second end plates 15 and 17, and oil supply means capable of dripping oil are provided on the outer circumferential surfaces of the first and second end plates 15 and 17.

[0076] Furthermore, in the above embodiment, relatively shallow recesses 16 and 18 are formed to suppress an increase in the rotational resistance of the rotor 10. However, the embodiment is not limited to this, and for example, as shown in the upper part of Figure 9, a relatively deep recess 16 (recess 18) may be formed that exposes the radially inner permanent magnet 13. In this case, it is preferable to form the recess 16 (recess 18) in a way that suppresses the protrusion of the permanent magnet 13 and does not interfere with the rotor's internal oil passage 15a, etc.

[0077] Furthermore, in the above embodiment, recesses 16 and 18 are formed in the shape of grooves extending in the circumferential direction. However, the embodiment is not limited to this, and for example, as shown in the lower part of Figure 9, shorter recesses 16 (recesses 18) may be formed in the circumferential direction in order to increase the number of permanent magnets 13 that are cooled.

[0078] Thus, the embodiments described above are merely illustrative in all respects and should not be interpreted restrictively. Furthermore, any modifications or changes that fall within the equivalent scope of the claims are all within the scope of the present invention. [Industrial applicability]

[0079] According to the present invention, even when it is difficult to form oil passages in a rotating body, the radially inner side of the permanent magnets and coil ends in the rotor can be cooled with a simple configuration, making it extremely useful when applied to the cooling structure of a rotating electric machine. [Explanation of Symbols]

[0080] 1. Motor (rotating electric machine) 10 rotors 11 rotor core 13 Permanent Magnets 15. First End Plate 16 recesses 17. Second end plate 18 recesses 20 stata 23 Stator Coil 23a First coil end 23b Second coil end 40b Second group of through holes (oil supply means) 43 Space (means of supplying oil) 45 Oil inlet (oil supply means) 72 Second oil supply unit (oil supply means)

Claims

1. A cooling structure for a rotating electric machine comprising a rotor having a cylindrical rotor core in which permanent magnets extending in the axial direction are embedded, and a stator having stator coils mounted on it, which is arranged radially outward from the rotor core, An end plate attached to the axial end of the rotor core, The outer circumferential surface of the end plate is further provided with an oil supply means capable of dripping oil, On the outer circumferential surface of the end plate, a recess is formed in the axial direction, with the portion on the rotor core side being radially recessed, so as to overlap radially with the coil end of the stator coil. The cooling structure for a rotating electric machine is characterized in that the recess is formed in a position and shape that exposes the axial end of the permanent magnet.

2. In the cooling structure for a rotating electric machine according to claim 1, The cooling structure for a rotating electric machine is characterized in that the recess is formed to expose at least the axial end of the permanent magnet that is located radially outward of the rotor core.

3. In the cooling structure for a rotating electric machine according to claim 1, The cooling structure for a rotating electric machine is characterized in that the recess is formed in the shape of a groove extending in the circumferential direction of the end plate.

4. In the cooling structure for a rotating electric machine according to claim 1, The cooling structure for a rotating electric machine is characterized in that the recesses are provided in multiple locations at equal intervals in the circumferential direction of the end plate.

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