Cooling structure for rotating electrical machinery

Abstract

This invention provides a cooling structure for a rotating electric machine that can cool the permanent magnets inside the rotor with a simple configuration, even when it is difficult to supply oil from the rotor shaft to the rotor. [Solution] This is a cooling structure for a rotating electric machine equipped with a cylindrical rotor in which permanent magnets are embedded. It further includes a cooling block 30, which is a non-rotating body, having an oil space 32 inside and a circumferential outer surface in which ejection holes 39 are formed for ejecting oil supplied to the oil space 32 in the radial direction. The cooling block 30 is positioned such that its outer surface is close to the inner surface of the rotor inner cylinder 19 so that an air gap G is formed between its outer surface and the inner surface of the rotor inner cylinder 19. The rotor has internal rotor oil passages 63a, 63b, and 63c formed at axial positions corresponding to the ejection holes 39, extending radially outward from the inner surface of the rotor inner cylinder 19 and communicating with the magnet holes.

Description

Technical Field

[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] When increasing the output density of a motor, it is inevitable to increase the density of the current flowing through the stator coil. However, in a synchronous motor, when the current density is increased, the amount of heat generated by 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.

[0004] Therefore, various structures for cooling the permanent magnet inside the rotor core have been conventionally proposed. Many of them adopt a structure that supplies cooling oil from an oil passage extending axially formed inside the rotor shaft to the vicinity of the permanent magnet embedded in the rotor core (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, 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., so it is conceivable that it may be 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.

[0007] This is because supplying oil to a rotating rotor shaft from a direction other than the axial direction is technically difficult unless a very complex structure is adopted, and adopting such a complex structure may be contrary to the miniaturization of the motor.

[0008] 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 permanent magnets inside the rotor with a simple configuration, even when it is difficult to supply oil from the rotor shaft to the rotor. [Means for solving the problem]

[0009] To achieve the above objective, the cooling structure for a rotating electric machine according to the present invention supplies oil to the inner circumferential surface of the rotor from a cooling block, which is a non-rotating body located radially inside the cylindrical rotor, by utilizing the negative pressure generated by the rotation of the rotor to supply oil to the permanent magnet.

[0010] Specifically, the present invention relates to a cooling structure for a rotating electric machine that has a cylindrical rotor in which permanent magnets extending in the axial direction are embedded.

[0011] Furthermore, the cooling structure of this rotating electric machine further comprises a cooling block, which is a non-rotating body having a circumferential outer surface with an oil space inside into which oil is supplied, and with ejection holes formed therein for ejecting the oil supplied to the oil space in the radial direction, wherein the cooling block is positioned radially inward of the rotor with its outer surface close to the inner surface of the rotor such that an air gap is formed between the outer surface and the inner surface of the rotor, and the rotor has an internal oil passage formed therein that extends radially outward from the inner surface of the rotor at an axial position corresponding to the ejection holes and communicates with a hole that extends axially near the permanent magnet, or a magnet hole into which the permanent magnet is inserted.

[0012] With this configuration, the cooling block, unlike the rotor shaft, is a non-rotating body, making it possible to easily supply oil to its internal oil space without employing a complex structure.

[0013] In such a cooling block, the circumferential outer surface, which has ejection holes for radially ejecting oil supplied to the oil space, is positioned radially inward of the rotor, close to the inner surface of the rotor, so that an air gap is formed between the outer surface and the inner surface of the rotor. This allows oil to be supplied from the oil space inside the cooling block to the air gap.

[0014] Here, since the rotor has internal oil passages that extend radially outward from its inner circumferential surface, the centrifugal force accompanying the rotor's rotation generates negative pressure in the internal oil passages, drawing the fluid radially outward. As the internal oil passages extend radially outward at axial positions corresponding to the injection holes, the oil supplied from the oil space inside the cooling block to the air gap flows radially outward through the internal oil passages due to the negative pressure, and is then supplied to holes extending axially near the permanent magnets, or to magnet holes into which the permanent magnets are inserted. Thus, the permanent magnets can be cooled by the oil supplied from the cooling block.

[0015] As described above, according to the present invention, with a simple configuration in which a cooling block, which is a non-rotating body, is placed radially inside the cylindrical rotor, it is possible to cool the permanent magnets inside the rotor even when it is difficult to supply oil from the rotor shaft to the rotor.

[0016] Furthermore, in the cooling structure for the rotating electric machine described above, the cooling block comprises an annular block body portion having an annular space formed inside as the oil space, an annular ring portion arranged radially outside the block body portion and having a plurality of ejection holes formed radially through at equal intervals in the circumferential direction, and a plurality of connecting portions extending radially at circumferential positions corresponding to the ejection holes and connecting the outer circumferential surface of the block body portion and the inner circumferential surface of the ring portion, and an oil passage connecting the oil space and the ejection holes may be formed inside each of the connecting portions.

[0017] Incidentally, if a configuration is adopted in which oil is supplied to the air gap from a specific position in the oil space of the cooling block, it is conceivable that variations may occur in the amount of oil supplied to the magnet holes, etc. If such variations in oil volume occur, the cooling of some of the permanent magnets embedded in the rotor core may become insufficient, potentially causing some permanent magnets to demagnetize and resulting in a decrease in torque.

[0018] In this respect, with this configuration, the cooling block has an annular block body with an annular space formed inside as an oil space, an annular ring portion with multiple ejection holes formed at equal intervals in the circumferential direction, and multiple connecting portions with oil passages formed inside that connect the oil space and the ejection holes. As a result, the oil supplied to the cooling block first spreads evenly throughout the annular oil space, then reaches the annular ring portion through the oil passages of the multiple connecting portions, and is supplied evenly to the air gap from the multiple ejection holes formed at equal intervals in the circumferential direction. This suppresses variations in the amount of oil supplied to the air gap in the circumferential direction, thereby preventing insufficient cooling of some permanent magnets.

[0019] In addition, since the cooling block has an annular block body, for example, the rotor shaft can be inserted radially inward into the block body, making it possible to install the cooling block even in a narrow space.

[0020] Furthermore, in the above-described cooling structure for the rotating electric machine, the rotor internal oil passage may include a chamber space formed concentrically with the rotor's axis inside the rotor and having an annular shape when viewed in the axial direction, a connecting oil passage extending radially outward from the inner circumferential surface of the rotor and communicating with the radially inner side of the chamber space, and a branching oil passage connecting the chamber space and the magnet hole.

[0021] With this configuration, the oil that flows from the air gap to the connecting oil passage due to the action of negative pressure is first filled into the annular chamber space and then supplied to the magnet holes through the branched oil passages. This suppresses variations in the amount of oil supplied to the magnet holes in the circumferential direction, thereby reliably preventing insufficient cooling for some permanent magnets.

[0022] In addition, in the cooling structure of the rotating electrical machine, it further includes a stator to which a stator coil is attached and which is disposed on the radially outer side of the rotor. The cooling block is disposed at one axial end portion on the radially inner side of the rotor so as to overlap with one axial end of the stator coil in the axial direction when viewed in the radial direction. The internal oil passage in the rotor may further have a first diffusion oil passage whose radially inner end communicates with the chamber space and extends radially outward to open at the outer peripheral surface of the rotor.

[0023] According to this configuration, the cooling block is disposed so as to overlap with one axial end of the stator coil in the axial direction when viewed in the radial direction, and the internal oil passage in the rotor has a first diffusion oil passage whose radially inner end communicates with the chamber space and extends radially to open at the outer peripheral surface of the rotor. Therefore, through the first diffusion oil passage, a part of the oil filled in the chamber space can be supplied to one axial end of the coil by the centrifugal force accompanying the rotation of the rotor.

[0024] Furthermore, in the cooling structure of the rotating electrical machine, a second diffusion oil passage may be formed in the rotor at the other axial end portion of the rotor so as to overlap with the other axial end of the stator coil in the axial direction when viewed in the radial direction, and whose radially inner end communicates with the magnet hole and extends radially outward to open at the outer peripheral surface of the rotor.

[0025] According to this configuration, the second diffusion oil passage is formed in the rotor at the other axial end portion of the rotor so as to overlap with the other axial end of the stator coil in the axial direction when viewed in the radial direction, and whose radially inner end communicates with the magnet hole and extends radially to open at the outer peripheral surface of the rotor. Therefore, through the second diffusion oil passage, the oil after cooling the permanent magnet can also be supplied to the other axial end of the coil by the centrifugal force accompanying the rotation of the rotor.

[0026] Further, in the cooling structure of the rotating electric machine, a housing for housing the rotor and the cooling block is further provided, and the cooling block may be fixed to the housing in advance.

[0027] Since the cooling block is arranged radially inside the rotor in a state where its outer peripheral surface is close to the inner peripheral surface of the rotor so that an air gap is formed between the outer peripheral surface and the inner peripheral surface of the rotor, high arrangement accuracy is required. According to this configuration, high arrangement accuracy can be achieved with a simple configuration of fixing the cooling block to the housing in advance.

[0028] Furthermore, in the cooling structure of the rotating electric machine, the rotor includes a cylindrical rotor core in which the permanent magnet is embedded, end plates attached to both axial ends of the rotor core, and a cylindrical rotor inner cylinder portion that is arranged radially inside the rotor core and connects the rotor core and the rotor shaft via an annular connecting portion at the central portion in the axial direction. The cooling block is arranged radially inside the rotor inner cylinder portion in a state where its outer peripheral surface is close to the inner peripheral surface of the rotor inner cylinder portion so that an air gap is formed between the outer peripheral surface and the inner peripheral surface of the rotor inner cylinder portion. The rotor internal oil passage may be composed of an oil introduction hole formed to penetrate radially at an axial position corresponding to the ejection hole in the rotor inner cylinder portion and an oil passage formed in the end plate.

[0029] According to this configuration, in a rotor having a cylindrical rotor core, end plates, and a rotor inner cylinder portion, a cooling structure of a rotating electric machine capable of cooling the permanent magnet inside the rotor can be realized.

[0030] In addition, since the cylindrical rotor inner cylinder portion connects the rotor core and the rotor shaft via an annular connecting portion at the central portion in the axial direction, it is possible to effectively utilize the space (annular space) between the rotor inner cylinder portion and the rotor shaft on both axial sides of the connecting portion.

Effect of the Invention

[0031] As described above, the cooling structure for a rotating electric machine according to the present invention allows for the cooling of permanent magnets inside the rotor with a simple configuration, even when it is difficult to supply oil from the rotor shaft to the rotor. [Brief explanation of the drawing]

[0032] [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] This is a schematic cross-sectional view of the rotor core. [Figure 4] This diagram schematically illustrates the oil passages formed in the first end plate. [Figure 5] This diagram schematically illustrates the oil passages formed in the first end plate. [Figure 6] This diagram schematically illustrates the oil passages formed in the second end plate. [Figure 7] This is a schematic perspective view showing the inner cylinder of the rotor. [Figure 8] This is a schematic perspective view of a cooling block. [Figure 9] This is a schematic perspective view showing the rotor with the cooling block positioned radially inward. [Figure 10] This is a partially enlarged perspective view schematically illustrating the oil flow from the cooling block. [Figure 11] This is a schematic perspective view illustrating a portion of the oil flow in a motor. [Modes for carrying out the invention]

[0033] The embodiments for carrying out the present invention will be described below with reference to the drawings.

[0034] -Overall motor configuration- Figure 1 is a schematic perspective view of the motor 1 according to this embodiment, and Figure 2 is a schematic longitudinal cross-sectional view of the main part of the motor 1. For convenience, in the following description, as shown in Figures 1 and 2, one side in the axial direction (the direction in which the rotor shaft 3 extends) (the left side in Figure 2) will be referred to as "one side ON," and the other side in the axial direction (the right side in Figure 2) will be referred to as "the other side OT." Also, in Figures 1 and 2, arrow U indicates the upper side, and arrow D indicates the lower side. Note that in Figure 2, a part of the stator coil 23 and the housing 50 are omitted from the illustration. Also, in Figure 2, hatching representing the cross-section is omitted for clarity.

[0035] 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.

[0036] 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.

[0037] -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.

[0038] <Rotor core and permanent magnet> Figure 3 is a schematic cross-sectional view of the rotor core 11. 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. Note that the parts of the magnet holes 11a that are not filled with permanent magnets 13, etc. (magnet holes 11b, 11c, 11d, 11e, 11f, 11g) remain as voids (flux barriers).

[0039] <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).

[0040] 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.

[0041] ≪First End Plate≫ [Third Plate] Figure 4 is a schematic diagram illustrating the oil passages formed in the first end plate 15. More specifically, the upper part of Figure 4 shows the ON side of the third plate 63, the middle part shows the OT side of the third plate 63, and the lower part shows the ON end face of the rotor core 11.

[0042] As shown in the upper part of Figure 4, the third plate 63 has a groove 63a' formed concentrically with the axis of the rotor 10, forming an annular groove when viewed in the axial direction, by recessing one side ON surface toward the other side OT surface. By overlapping the other side OT surface of the second plate 62 with the ON surface of the third plate 63 in which the groove 63a' is formed, the groove 63a' is covered, and an annular chamber space 63a is formed when viewed in the axial direction.

[0043] Furthermore, the third plate 63 has 12 grooves 63b' formed at equal intervals in the circumferential direction, extending radially outward from its inner circumferential surface and communicating with the radially inner side of groove 63a', by recessing one side ON toward the other side OT. By overlapping the other side OT surface of the second plate 62 with the ON side of the third plate 63 on which these grooves 63b' are formed, the grooves 63b' are covered, and 12 connecting oil passages 63b are formed, extending radially outward from the inner circumferential surface of the third plate 63 and communicating with the radially inner side of the chamber space 63a.

[0044] Furthermore, as shown in the upper and middle sections of Figure 4, the third plate 63 has 36 through holes 63c that penetrate the third plate 63 axially, spaced apart in the circumferential direction within the chamber space 63a. When the other side OT of the third plate 63 is superimposed on the end face ON of one side of the rotor core 11, these 36 through holes 63c communicate with radially inner magnet holes 11b, 11c, 11d, and 11e, which are voids, as shown by the black circles in the lower section of Figure 4.

[0045] Furthermore, as shown in the middle of Figure 4, the third plate 63 has 12 grooves 63d' that extend radially outward from the through hole 63c to positions corresponding to the radially outer magnet holes 11f and 11g, which are voids, by recessing the other side OT surface toward the one side ON. By overlapping the other side OT surface of the third plate 63, where these grooves 63d' are formed, with the one side ON end face of the rotor core 11, the grooves 63d' are covered, and 12 oil passages 63d that communicate with the magnet holes 11f and 11g are formed.

[0046] With the above configuration, when oil is supplied to the connecting oil passage 63b from the radially inner side, the oil that has passed through the 12 connecting oil passages 63b accumulates in the chamber space 63a and is then supplied to the 48 magnet holes 11b, 11c, 11d, 11e, 11f, and 11g via the 36 through holes 63c and the 12 oil passages 63d. Therefore, in relation to the claims, the through holes 63c and oil passages 63d in this embodiment correspond to the "branching oil passages that connect the chamber space and the magnet holes" as referred to in the present invention.

[0047] [Plate 2] Figure 5 is a schematic diagram illustrating the oil passages formed in the first end plate 15. More specifically, the upper part of Figure 5 shows the other side OT surface of the second plate 62, and the lower part of Figure 5 shows the one side ON surface of the second plate 62. As shown in the upper and lower parts of Figure 5, the second plate 62 has 12 through holes 62a that penetrate the second plate 62 axially at positions corresponding to the chamber space 63a.

[0048] Furthermore, as shown in the lower part of Figure 5, the second plate 62 has 12 grooves 62b' that extend radially outward from the through hole 62a and open on the outer circumferential surface of the second plate 62, by recessing one side ON surface toward the other side OT surface. By overlapping the other side OT surface of the first plate 61 with the ON surface of the second plate 62 in which these grooves 62b' are formed, the grooves 62b' are covered, and the radially inward ends communicate with the chamber space 63a via the through hole 62a, and 12 first diffusion oil passages 62b are formed that extend radially outward and open on the outer circumferential surface of the rotor 10. Note that each first diffusion oil passage 62b is formed such that the flow area increases as it extends radially outward.

[0049] With the above configuration, when oil is supplied to the connecting oil passage 63b from the radially inner side, the oil that has passed through the 12 connecting oil passages 63b accumulates in the chamber space 63a, and then a portion of it flows through the 12 through holes 62a into the first diffusion oil passage 62b, where it is diffused radially outward by the centrifugal force associated with the rotation of the rotor 10.

[0050] ≪Second End Plate≫ [Plate 4] Figure 6 is a schematic diagram illustrating the oil passages formed in the second end plate 17. More specifically, the upper part of Figure 6 shows the other end face OT of the rotor core 11, the middle part of Figure 6 shows the one side ON of the fourth plate 64, and the lower part of Figure 6 shows the other side OT of the fourth plate 64. As shown in the middle and lower parts of Figure 6, the fourth plate 64 has 36 through holes 64a that penetrate the fourth plate 64 axially at positions corresponding to the magnet holes 11b, 11d, 11f, and 11g (see the black circles in the upper part of Figure 6).

[0051] Furthermore, as shown in the lower part of Figure 6, the fourth plate 64 has 36 grooves 64b' formed by recessing the other side OT surface toward the one side ON, extending radially outward from the through hole 64a and opening on the outer circumferential surface of the fourth plate 64. By overlapping the one side ON surface of the fifth plate 65 with the other side OT surface of the fourth plate 64 where these grooves 64b' are formed, the grooves 64b' are covered, and the radially inward ends communicate with the magnet holes 11b, 11d, 11f, and 11g via the through hole 64a, and 36 second diffusion oil passages 64b are formed that extend radially outward and open on the outer circumferential surface of the rotor 10. Note that each second diffusion oil passage 64b is formed such that the flow area increases as it extends radially outward.

[0052] With the above configuration, the oil that flows through the magnet holes 11b, 11d, 11f, and 11g from one axial side ON to the other side OT while cooling the permanent magnet 13 flows through the 36 through holes 64a into the second diffusion oil passage 64b, and is diffused radially outward by the centrifugal force associated with the rotation of the rotor 10.

[0053] <Rotor inner cylinder section> Figure 7 is a schematic perspective view of the rotor inner cylinder portion 19. As shown in Figures 2 and 7, 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.

[0054] 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.

[0055] Furthermore, in the outer cylindrical portion 19a of the rotor inner cylindrical portion 19, an oil introduction hole 19d is formed through the portion (axial position) corresponding to the third plate 63 (connecting oil passage 63b), as shown in Figures 2 and 7, passing radially through the outer cylindrical portion 19a.

[0056] -Stator- As shown in Figure 2, the stator 20 includes 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 (not shown) that open radially inward. The stator coils 23 are mounted on the stator core 21 so as to be housed in the slots. The portion of the stator coil 23 protruding from one side ON from the slot constitutes the first coil end 23a, and the portion protruding from the other side OT from the slot 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.

[0057] -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 (above) 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 circumferential 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.

[0058] In the portion of the motor cover 40 that overlaps with the shell cover 41, multiple groups of through-holes (not shown) are formed at axial intervals, each consisting of multiple through-holes that penetrate the motor cover 40 radially and are arranged circumferentially. These groups allow oil to be supplied to different cooling targets within the motor cover 40 (for example, the stator core 21, the first and second coil ends 23a, 23b, etc.). As a result, when oil is supplied into the space 43 from the second oil supply unit 72 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 through the groups of through-holes arranged circumferentially.

[0059] -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.

[0060] 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.

[0061] -Cooling Block- 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.

[0062] Therefore, it is conceivable to cool the permanent magnets 13 inside the rotor core 11 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 a spatial design constraint where another device (not shown) exists on one axial side of the motor 1 when it is ON, 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).

[0063] 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.

[0064] Figure 8 is a schematic perspective view of the cooling block 30, Figure 9 is a schematic perspective view of the cooling block 30 positioned radially inward of the rotor 10, and Figure 10 is a partially enlarged perspective view schematically illustrating the oil flow from the cooling block 30. The cooling block 30 is a non-rotating body pre-fixed to the first housing cover 53, and has an oil space 32 inside to which oil is supplied, and a circumferential outer surface with ejection holes 39 formed therein for ejecting the oil supplied to the oil space 32 radially.

[0065] More specifically, as shown in Figure 8, the cooling block 30 includes an annular block body portion 31, an annular ring portion 33 positioned radially outward from the block body portion 31, six 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.

[0066] As shown in Figure 10, an annular space is formed inside the annular block body 31, which serves as an oil space 32 to which oil is supplied. Six ejection holes 39 are formed in the annular ring portion 33 at equal intervals (60° intervals) in the circumferential direction, penetrating the ring portion 33 radially. Six 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.

[0067] As shown in Figures 2 and 9, 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.

[0068] Furthermore, as shown in Figures 2, 9, and 10, the cooling block 30 is positioned radially inward of the rotor 10 with its outer circumferential surface close to the inner circumferential surface of the rotor 10, such that an air gap G is formed between its outer circumferential surface and the inner circumferential surface of the rotor 10. More specifically, the cooling block 30 is positioned radially inward of the rotor inner cylinder portion 19 with its outer circumferential surface close to the inner circumferential surface of the rotor inner cylinder portion 19, such that an air gap G is formed between the outer circumferential surface of the ring portion 33 and the inner circumferential surface of the rotor inner cylinder portion 19. At this time, the rotor shaft 3 is inserted radially inward of the annular block body portion 31.

[0069] 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 will accumulate evenly in the annular oil space 32. The oil accumulated evenly in the oil space 32 will then be supplied through the oil passage 36 formed inside the connecting unit 35, as shown by the black arrows in Figure 10, to the air gap G between the outer circumferential surface of the ring unit 33 and the inner circumferential surface of the rotor inner cylinder 19, via the six ejection holes 39 formed in the ring unit 33.

[0070] As shown by the thick arrows in Figure 10, the rotor 10 is rotating, and therefore, due to the centrifugal force associated with the rotation of the rotor 10, negative pressure is generated in the radially extending connecting oil passages 63b, 63d, and the first diffusion oil passage 62b, drawing 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 inner cylinder 19, as shown by the white arrows in Figure 10, and after passing through the 12 connecting oil passages 63b and accumulating in the chamber space 63a, it is supplied to the magnet holes 11b, 11c, 11d, 11e, 11f, and 11g via the 36 through holes 63c and 12 oil passages 63d. This makes it possible to directly cool the permanent magnet 13 by realizing a cooling path as shown by the thick arrow A in Figure 11 using the oil supplied from the non-rotating cooling block 30. Therefore, in relation to the claims, the oil introduction hole 19d, connecting oil passage 63b, chamber space 63a, through hole 63c and oil passage 63d of this embodiment correspond to the "oil passage inside the rotor that extends radially outward from the inner circumferential surface at an axial position corresponding to the ejection hole and communicates with a magnet hole into which a permanent magnet is inserted" as described in the present invention.

[0071] Furthermore, since the first coil end 23a overlaps with the first end plate 15 when viewed radially, a portion of the oil accumulated in the chamber space 63a flows through the 12 through holes 62a into the first diffusion oil passage 62b, where it is diffused radially outward by the centrifugal force associated with the rotation of the rotor 10 and supplied to the first coil end 23a from the radially inward side. As a result, the oil supplied from the non-rotating cooling block 30 creates a cooling path as shown by the thick arrow B in Figure 11, making it possible to cool the first coil end 23a as well.

[0072] Furthermore, since the second coil end 23b overlaps with the second end plate 17 in the radial direction, the oil that flows through the magnet holes 11b, 11d, 11f, and 11g from one axial side ON to the other side OT while cooling the permanent magnet 13 flows through the 36 through holes 64a into the second diffusion oil passage 64b, 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 inward side. As a result, the oil supplied from the non-rotating cooling block 30 realizes a cooling path as shown by the thick arrow C in Figure 11, making it possible to cool the second coil end 23b as well.

[0073] -Effects- According to the cooling structure for a rotating electric machine of this embodiment, the cooling block 30 is a non-rotating body, unlike the rotor shaft 3, so it is possible to easily supply oil to the oil space 32 inside it without employing a complex structure.

[0074] The cooling block 30 is positioned radially inward of the rotor 10, close to the inner surface of the rotor inner cylinder 19, so that the outer circumferential surface of the ring portion 33, which has ejection holes 39 for ejecting oil supplied to the oil space 32 in the radial direction, is close to the inner circumferential surface of the rotor inner cylinder 19, and an air gap G is formed between the outer circumferential surface and the inner circumferential surface of the rotor inner cylinder 19. This allows oil to be supplied from the oil space 32 inside the cooling block 30 to the air gap G.

[0075] Here, since the rotor 10 has internal oil passages (connecting oil passages 63b, oil passages 63d, ...) that extend radially outward from its inner circumferential surface, the centrifugal force accompanying the rotation of the rotor 10 generates negative pressure in the internal oil passages (chamber space 63a, connecting oil passages 63b, through holes 63c, ...) that draws the fluid radially outward. As the connecting oil passage 63b extends radially outward at an axial position corresponding to the ejection hole 39, the oil supplied from the oil space 32 inside the cooling block 30 to the air gap G flows radially outward through the connecting oil passage 63b due to the negative pressure, and then is supplied to the magnet holes 11b, 11c, 11d, 11e, 11f, 11g into which the permanent magnets 13 are inserted. Thus, the permanent magnets 13 can be cooled by the oil supplied from the cooling block 30.

[0076] As described above, according to this embodiment, with a simple configuration in which a cooling block 30, which is a non-rotating body, is placed radially inside the cylindrical rotor 10, the permanent magnets 13 inside the rotor 10 can be directly cooled even when it is difficult to supply oil from the rotor shaft 3 to the rotor 10.

[0077] Furthermore, the cooling block 30 has an annular block body portion 31 with an annular space formed inside as an oil space 32, an annular ring portion 33 with six ejection holes 39 formed at equal intervals in the circumferential direction, and six connecting portions 35 with oil passages 36 formed inside that connect the oil space 32 and the ejection holes 39. As a result, the oil supplied to the cooling block 30 first spreads evenly throughout the oil space 32, then reaches the annular ring portion 33 through the oil passages 36 of the six connecting portions 35, and is supplied evenly to the air gap G from the six ejection holes 39 formed at equal intervals in the circumferential direction. This suppresses variations in the amount of oil supplied to the air gap G in the circumferential direction, thereby preventing insufficient cooling of some of the permanent magnets 13.

[0078] In addition, since the cooling block 30 has an annular block body portion 31, for example, the rotor shaft 3 can be inserted radially inward into the block body portion 31, thereby making it possible to install the cooling block 30 even in a narrow space.

[0079] Furthermore, the oil flowing from the air gap G to the connecting oil passage 63b due to the negative pressure is first filled into the annular chamber space 63a, and then supplied to the magnet holes 11b, 11c, 11d, 11e, 11f, and 11g through the branched oil passages (through holes 63c, oil passage 63d). This suppresses circumferential variation in the amount of oil supplied to the magnet holes 11b, 11c, 11d, 11e, 11f, and 11g, thereby reliably preventing insufficient cooling for some of the permanent magnets 13.

[0080] Furthermore, the first end plate 15 has a first diffusion oil passage 62b formed therein, which extends radially outward and opens on the outer circumferential surface of the rotor 10, with its radially inward end communicating with the chamber space 63a through a through hole 62a. As a result, a portion of the oil filling the chamber space 63a can be supplied to the first coil end 23a through the first diffusion oil passage 62b by the centrifugal force associated with the rotation of the rotor 10.

[0081] Furthermore, the second end plate 17 has a second diffusion oil passage 64b formed at the end of the rotor 10 on the other axial side OT, where the radially inner end communicates with the magnet holes 11b, 11d, 11f, and 11g via a through hole 64a, and extends radially outward to open on the outer circumferential surface of the rotor 10. As a result, the oil used to cool the permanent magnet 13 can be supplied to the second coil end 23b through the second diffusion oil passage 64b by the centrifugal force associated with the rotation of the rotor 10.

[0082] Furthermore, since the cooling block 30 is positioned radially inward of the rotor 10 with its outer surface close to the inner surface of the rotor inner cylinder 19, such that an air gap G is formed between its outer surface and the inner surface of the rotor inner cylinder 19, high positional accuracy is required. However, high positional accuracy can be achieved with a simple configuration in which the cooling block 30 is pre-fixed to the first housing cover 53.

[0083] Furthermore, since the cylindrical rotor inner cylinder portion 19 connects the inner surface of the rotor core 11 and the outer surface of the rotor shaft 3 via an annular connecting portion 19c at its axial center, it becomes possible to effectively utilize the spaces S1 and S2 (annular spaces) between the rotor inner cylinder portion 19 and the rotor shaft 3 on both axial sides of the connecting portion 19c.

[0084] (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.

[0085] In the above embodiment, the cooling block 30 was configured to have a block body portion 31, a ring portion 33, and a connecting portion 35. However, it is not limited to this configuration, as long as it has an oil space 32 inside and a circumferential outer surface with ejection holes 39 formed therein for ejecting oil supplied to the oil space 32 in the radial direction. For example, an annular or disc-shaped cooling block 30 may be used, which has an oil space 32 and an oil passage 36 inside and has ejection holes 39 provided on its outer surface.

[0086] Furthermore, in the above embodiment, the oil is supplied directly to the magnet holes 11b, 11c, 11d, 11e, 11f, and 11g. However, the invention is not limited to this, and for example, the oil may be supplied to holes (not shown) formed in the rotor core 11 that extend axially near the permanent magnets 13.

[0087] Furthermore, in the above embodiment, the first diffusion oil passage 62b and the second diffusion oil passage 64b are provided in the rotor 10 (first and second end plates 15, 17). However, as long as an oil passage is formed in the rotor 10 that extends radially outward from the inner circumferential surface of the rotor 10 at an axial position corresponding to the ejection hole 39 and communicates with the magnet holes 11b, 11c, 11d, 11e, 11f, 11g, the first diffusion oil passage 62b and the second diffusion oil passage 64b do not need to be provided.

[0088] Furthermore, although the above embodiment provides a chamber space 63a in the rotor 10, the invention is not limited to this, and the chamber space 63a may be omitted if an oil passage is formed in the rotor 10 that extends radially outward from the inner circumferential surface of the rotor 10 at an axial position corresponding to the ejection hole 39 and communicates with the magnet holes 11b, 11c, 11d, 11e, 11f, and 11g.

[0089] Furthermore, in the above embodiment, the present invention is applied to a so-called T-shaped rotor structure in which the inner circumferential surface of the rotor core 11 and the outer circumferential surface of the rotor shaft 3 are connected via a connecting portion 19c. However, the present invention is not limited to this, and may also be applied to a rotor structure in which the rotor shaft 3 is fitted into the central hole of the rotor core 11.

[0090] 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]

[0091] According to the present invention, even when it is difficult to supply oil from the rotor shaft to the rotor, the permanent magnets inside 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]

[0092] 1. Motor (rotating electric machine) 3. Rotor shaft 10 rotors 11 rotor core 11a Magnet hole 13 Permanent Magnets 15. First End Plate 17. Second end plate 19 Rotor inner cylinder 19d Oil inlet hole (oil passage inside the rotor) 20 staters 23 Stator Coil 23a First coil end 23b Second coil end 30 Cooling Blocks 31 Block main body 32 Oil Space 33 Ring section 35 Connecting part 36 Oil road 39 Spout hole 50 Housing 62b First diffusion oil passage (oil passage inside the rotor) 63a Chamber space (oil passage inside the rotor) 63b Connection oil passage (rotor internal oil passage) 63c Through-hole (branch oil passage) (oil passage inside rotor) 63d Oil path (branch oil path) (rotor internal oil path) 64b Second diffusion oil passage (oil passage inside the rotor) G Air Gap

Claims

1. A cooling structure for a rotating electric machine having a cylindrical rotor in which permanent magnets extending in the axial direction are embedded, The cooling block is a non-rotating body having a circumferential outer surface with an oil space inside into which oil is supplied, and with ejection holes formed therein for ejecting the oil supplied to the oil space in the radial direction. The cooling block is positioned radially inward of the rotor, with its outer surface close to the inner surface of the rotor, such that an air gap is formed between the outer surface and the inner surface of the rotor. A cooling structure for a rotating electric machine, characterized in that the rotor has an internal oil passage that communicates with a hole that extends radially outward from the inner circumferential surface of the rotor at an axial position corresponding to the ejection hole, and also extends axially near the permanent magnet, or a magnet hole into which the permanent magnet is inserted.

2. In the cooling structure for a rotating electric machine according to claim 1, The cooling block is, The annular block body portion has an annular space formed inside which serves as the oil space, The block body is arranged radially outward, and a plurality of the ejection holes are formed radially through the annular ring portion, with the holes being equally spaced in the circumferential direction. It has a plurality of connecting parts that extend radially at circumferential positions corresponding to the ejection holes and connect the outer circumferential surface of the block body and the inner circumferential surface of the ring portion, A cooling structure for a rotating electric machine, characterized in that an oil passage is formed inside each of the aforementioned connecting parts, connecting the oil space and the ejection hole.

3. In the cooling structure for a rotating electric machine according to claim 1, The aforementioned oil passage inside the rotor is Inside the rotor, there is a chamber space formed concentrically with the axis of the rotor, which is annular in shape when viewed in the axial direction. A connecting oil passage extends radially outward from the inner circumferential surface of the rotor and communicates with the radially inner side of the chamber space, A cooling structure for a rotating electric machine, characterized by having a branched oil passage that connects the chamber space and the magnet hole.

4. In the cooling structure for a rotating electric machine described in claim 3, The rotor is further provided with a stator, which is positioned radially outward from the rotor and is fitted with a stator coil. The cooling block is positioned at the axial end of the rotor, on the radially inward side, so as to overlap with the axial coil end of the stator coil in the radial direction. A cooling structure for a rotating electric machine, characterized in that the oil passage inside the rotor has a first diffusion oil passage whose radially inner end communicates with the chamber space and which extends radially outward and opens on the outer circumferential surface of the rotor.

5. In the cooling structure for a rotating electric machine according to claim 4, A cooling structure for a rotating electric machine, characterized in that the rotor has a second diffusion oil passage formed at the end of the rotor on the other axial side, such that it overlaps radially with the coil end on the other axial side of the stator coil, with the radially inner end communicating with the magnet hole and extending radially outward to open on the outer circumferential surface of the rotor.

6. In the cooling structure for a rotating electric machine according to claim 1, The housing further comprises the rotor and the cooling block, A cooling structure for a rotating electric machine, characterized in that the cooling block is fixed in advance to the housing.

7. In the cooling structure for a rotating electric machine according to claim 1, The rotor is A cylindrical rotor core in which the aforementioned permanent magnet is embedded, End plates attached to both ends in the axial direction of the rotor core, It has a cylindrical rotor inner cylinder portion that is positioned radially inward of the rotor core and connects the rotor core and the rotor shaft via an annular connecting portion at the axial center, The cooling block is positioned radially inward of the rotor inner cylinder, with its outer surface close to the inner surface of the rotor inner cylinder, such that an air gap is formed between the outer surface and the inner surface of the rotor inner cylinder. The aforementioned oil passage inside the rotor is In the rotor inner cylinder portion, an oil introduction hole is formed radially through at an axial position corresponding to the ejection hole, A cooling structure for a rotating electric machine, characterized by comprising an oil passage formed in the end plate.

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