Rotary electric machine

Abstract

To provide a rotary electric machine in which the reliability of a rotor is increased than before while a permanent magnet is cooled.SOLUTION: A rotary electric machine 1 includes a rotor 3 having a permanent magnet 8, a shaft 2 supporting the rotor 3 in a freely rotatable manner, and an inner rotor passage into which cooling oil flows from an inner shaft passage 5 disposed in the shaft 2. The inner rotor passage has a second inflow port 43 that is open on an inner circumferential surface of the rotor 3, an upstream side passage 40 extending radially outward from the second inflow port 43, and a downstream side passage 50 connected to the upstream side passage 40 and extending in an axial direction. The upstream side passage 40 includes a first upstream side passage 41 and a second upstream side passage 42 arranged in the circumferential direction of the rotor 3. A first radial position R1 at an outer circumferential end of the first upstream side passage 41 is set at a radially inner position than a second radial position R2 at an outer circumferential end of the second upstream side passage 42.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine that can be used, for example, as a drive source for an electric vehicle. [Background technology]

[0002] Conventionally, cooling techniques for permanent magnets provided in rotating electrical machines have been proposed. For example, in Patent Document 1, cooling oil is supplied to a coolant flow path provided inside a rotor through a coolant passage provided inside a shaft. The permanent magnets are cooled by the cooling oil flowing through the coolant flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-176235 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when a rotor contains different media (e.g., electromagnetic steel sheets, permanent magnets, air gaps, etc.) depending on the circumferential position, the mechanical properties may differ depending on the circumferential position. If a refrigerant flow path such as that described in Patent Document 1 is provided in the rotor without considering the difference in mechanical properties depending on the circumferential position, a portion with relatively low mechanical properties may be created at a certain circumferential position on the rotor. If local stress concentration occurs due to centrifugal force during rotation of the rotor in this portion with relatively low mechanical properties, this may affect the reliability of the rotor.

[0005] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a rotating electric machine that is capable of cooling permanent magnets while improving the reliability of the rotor compared to conventional techniques. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a rotating electrical machine, comprising a rotor having a permanent magnet, a shaft rotatably supporting the rotor, an inner passage of the shaft provided inside the shaft, and a rotor inner passage through which a liquid refrigerant flows from the inner passage of the shaft via an inlet opening on the inner peripheral surface of the rotor. The rotor inner passage has an upstream passage extending radially outward from the inlet and a downstream passage connected to the upstream passage and extending axially. The upstream passage includes a first upstream passage and a second upstream passage arranged in the circumferential direction of the rotor, and the radial position of the outer peripheral end of the first upstream passage is set to a position radially outside or radially inside the radial position of the outer peripheral end of the second upstream passage.

[0007] According to the present invention configured as described above, the permanent magnet can be cooled by the liquid refrigerant flowing from the inner passage of the shaft into the rotor inner passage. Further, by making the radial position of the outer peripheral end of the first upstream passage different from the radial position of the outer peripheral end of the second upstream passage, it is possible to make the difference in the mechanical characteristics of the rotor, which varies according to the circumferential position, smaller than before. As a result, even when local stress concentration due to centrifugal force occurs during rotor rotation, it is possible to suppress the influence on the reliability of the rotor.

[0008] In the present invention, preferably, the first upstream passage extends along the q-axis direction, and the second upstream passage extends along the d-axis direction.

[0009] According to the present invention configured as described above, by making the radial position of the outer peripheral end of the first upstream passage extending along the q-axis direction different from the radial position of the outer peripheral end of the second upstream passage extending along the d-axis direction, it is possible to make the difference in the mechanical characteristics of the rotor occurring between the circumferential position corresponding to the q-axis direction and the circumferential position corresponding to the d-axis direction smaller than before.

[0010] In the present invention, the first upstream passages and the second upstream passages are preferably provided alternately in the circumferential direction of the rotor.

[0011] According to the present invention configured as described above, the first upstream passages and the second upstream passages are provided alternately in the circumferential direction of the rotor, which makes it possible to further reduce the difference in mechanical characteristics of the rotor that differs depending on the circumferential position compared to the conventional art.

[0012] In the present invention, the outer circumferential portion of the upstream passage is preferably configured so that the axial cross section thereof is elliptical.

[0013] According to the present invention configured as described above, the axial cross section of the outer circumferential portion of the upstream passage is elliptical, which makes the radius of curvature of the outer circumferential end of the upstream passage larger than that of a circular shape, thereby making it possible to disperse stress acting on the outer circumferential end of the upstream passage during rotor rotation, for example.

[0014] In the present invention, preferably, the inlet is provided in an axial central portion of the rotor, the downstream passage has a first downstream passage provided on one axial side of the upstream passage and a second downstream passage provided on the other axial side of the upstream passage, the radial position of an outer circumferential end of the first upstream passage is set to a position radially inward relative to the radial position of an outer circumferential end of the second upstream passage, and a connecting passage extending in the axial direction and connecting the first downstream passage and the second downstream passage is provided radially outward of the first upstream passage.

[0015] According to the present invention configured as described above, since the inlet is provided in the axial center portion of the rotor, it is possible to preferentially cool the axial center portion of the permanent magnet, which is most likely to have a high temperature, over other portions using the liquid refrigerant flowing from the inner passage in the shaft into the upstream passage. Thereby, it is possible to suppress the axial center portion of the permanent magnet from becoming high temperature. Further, by setting the radial position of the outer peripheral end of the first upstream passage provided on the radially inner side of the connection passage to be radially inner than the radial position of the outer peripheral end of the second upstream passage, it is possible to reduce the difference in mechanical characteristics that occurs between the circumferential position where the first upstream passage and the connection passage are provided and the circumferential position where the second upstream passage is provided.

[0016] In the present invention, preferably, it further has a stator provided on the radially outer side of the rotor, a coil end provided at the axial end of the stator, an end plate provided at the axial end of the rotor, and an outflow passage provided in the end plate and extending in the radial direction. The inner peripheral portion of the outflow passage is connected to the downstream passage, and the outlet provided at the outer peripheral end faces the coil end.

[0017] According to the present invention configured as described above, the liquid refrigerant used for cooling the permanent magnet when passing through the downstream passage flows out from the outlet and is supplied to the coil end. Thereby, the liquid refrigerant after cooling the permanent magnet can also be used for cooling the coil end.

[0018] In the present invention, preferably, the rotor and the shaft are fixed by shrink fitting.

[0019] According to the present invention configured as described above, since the rotor and the shaft are fixed by shrink fitting, the rotor and the shaft can be securely fixed. Further, the shrink fitting stress acting on the rotor can be relaxed by the upstream passage extending radially outward from the inlet opening on the inner peripheral surface of the rotor. Thereby, the reliability of the rotor can be further enhanced.

Advantages of the Invention

[0020] It is possible to provide a rotating electric machine that can improve the reliability of the rotor compared to conventional methods while cooling the permanent magnets. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view showing a rotating electric machine according to an embodiment of the present invention; [Diagram 2] FIG. 4 is a view showing a portion of a first electromagnetic steel sheet. [Diagram 3] FIG. 4 is a view showing a portion of a second electromagnetic steel sheet. [Figure 4] FIG. 2 is a schematic cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 2 is a schematic cross-sectional view taken along line VV in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: It should be noted that the following description of the preferred embodiments is merely exemplary in nature.

[0023] 1 shows a rotating electric machine 1 according to an embodiment of the present invention. The rotating electric machine 1 is an embedded magnet type electric motor that can be used, for example, as a drive source for an electric vehicle.

[0024] The rotating electric machine 1 includes a shaft 2, a rotor 3 fixed to the outer circumferential surface of the shaft 2, and a stator 4 disposed radially outside the rotor 3 at a predetermined distance from the rotor 3. The shaft 2 rotatably supports the rotor 3. The axial end of the stator 4 is provided with a coil end 4a.

[0025] The shaft 2 is axially shaped and rotatably supported via bearings (not shown) in a case (not shown) of the rotating electrical machine 1. Further, inside the shaft 2, an inner shaft passage 5 is provided.

[0026] The shaft internal passage 5 is provided with a first shaft internal passage 5a extending axially inside the shaft 2 and a plurality of second shaft internal passages 5b extending radially inside the shaft 2.

[0027] One axial end of the first shaft internal passage 5a is closed. Also, a first inlet 5c is provided at the other axial end of the first shaft internal passage 5a. And cooling oil (liquid refrigerant) is supplied from the oil pump 6 to the first shaft internal passage 5a through the first inlet 5c. In this embodiment, the oil pump 6 is driven by the shaft 2 or a power transmission shaft between the shaft 2 and a wheel (not shown).

[0028] The torque generated by the rotating electric machine 1 is transmitted to a wheel (not shown) through a speed reducer (not shown). And the cooling oil supplied from the oil pump 6 to the first shaft internal passage 5a can also be used as the lubricating oil of the speed reducer (not shown). In other words, the cooling oil of the rotating electric machine 1 and the lubricating oil of the speed reducer (not shown) are shared. In this embodiment, the cooling oil is Automatic transmission fluid.

[0029] The plurality of second shaft internal passages 5b are arranged side by side at a predetermined interval in the circumferential direction of the shaft 2. The inner circumferential end of each second shaft internal passage 5b is connected to the axial center portion of the first shaft internal passage 5a. Also, a first outlet 5d is provided at the outer circumferential end of each second shaft internal passage 5b. In this embodiment, the first outlets 5d are provided at 22.5 degrees intervals in the circumferential direction on the outer circumferential surface of the shaft 2.

[0030] The rotor 3 is substantially cylindrical, and is fixed to the shaft 2 with the shaft 2 inserted into a through hole 3a formed in the center of the rotor 3. In this embodiment, the shaft 2 and the rotor 3 are fixed by shrink fitting. For example, the shrink fitting is performed by heating the rotor 3 to widen the through hole 3a of the rotor 3, inserting the shaft 2 into the through hole 3a, and then cooling the rotor 3 to narrow the through hole 3a, thereby fixing the rotor 3 and the shaft 2.

[0031] The rotor 3 also includes a rotor core 7, a plurality of permanent magnets 8 (for example, rare earth magnets such as neodymium), and a pair of end plates 9. The end plates 9 are substantially disk-shaped, and are disposed on both axial sides of the rotor core 7. In other words, the pair of end plates 9 are provided at axial ends of the rotor 3 so as to sandwich the rotor core 7 in the axial direction.

[0032] Furthermore, rotor core 7 is provided with a plurality of first electromagnetic steel sheets 20 and second electromagnetic steel sheets 30 each having a substantially disk shape. The first electromagnetic steel sheets 20 and the second electromagnetic steel sheets 30 are stacked in the axial direction to form rotor core 7. In this embodiment, the first electromagnetic steel sheets 20 are located in the axial center, and the second electromagnetic steel sheets 30 are located on both axial sides of the first electromagnetic steel sheets 20.

[0033] 2, the first electromagnetic steel sheet 20 is provided with a plurality of first slits 21 and second slits 22 extending radially outward from its inner circumferential surface. The first slits 21 and second slits 22 are arranged side by side at predetermined intervals in the circumferential direction. In this embodiment, the first slits 21 and the second slits 22 are arranged alternately every 22.5 degrees in the circumferential direction on the inner circumferential portion of the first electromagnetic steel sheet 20.

[0034] Furthermore, a plurality of third slits 23 extending in the circumferential direction are provided at positions radially outward of the plurality of first slits 21 and second slits 22 in the first electromagnetic steel sheet 20. The plurality of third slits 23 are arranged side by side at predetermined intervals in the circumferential direction. In this embodiment, the third slits 23 are provided every 45 degrees in the circumferential direction in a radial midpoint of the first electromagnetic steel sheet 20.

[0035] Furthermore, a plurality of fourth slits 24 are provided in the first electromagnetic steel sheet 20 at positions radially outward of the plurality of third slits 23, extending in a direction intersecting the radial direction.

[0036] 3, the second electromagnetic steel sheet 30 is provided with a plurality of fifth slits 31 each having a substantially trapezoidal shape when viewed in the axial direction. The plurality of fifth slits 31 are arranged side by side at predetermined intervals from each other in the circumferential direction. In this embodiment, the fifth slits 31 are provided at an inner peripheral portion and a radially middle portion of the second electromagnetic steel sheet 30 at 45° intervals in the circumferential direction.

[0037] Further, a plurality of sixth slits 32 are provided in the second electromagnetic steel sheet 30 at positions radially outward of the plurality of fifth slits 31, and extend in a direction intersecting the radial direction.

[0038] In this embodiment, the circumferential positions of the electromagnetic steel sheets (first electromagnetic steel sheet 20 and second electromagnetic steel sheet 30) are aligned so that the slits (first slit 21 to sixth slit 32) of the electromagnetic steel sheets (first electromagnetic steel sheet 20 and second electromagnetic steel sheet 30) communicate with each other in the axial direction, and then all the electromagnetic steel sheets (first electromagnetic steel sheet 20 and second electromagnetic steel sheet 30) constituting the rotor core 7 are stacked in the axial direction to form the upstream passage 40, the downstream passage 50, the connection passage 60, and the accommodation section 70 (see Figs. 1, 4, and 5). More specifically, the upstream passage 40 is formed by axially communicating the first slits 21 and the second slits 22 provided in all the first electromagnetic steel sheets 20 constituting the rotor core 7. The downstream passage 50 is formed by axially communicating the fifth slits 31 provided in all the second electromagnetic steel sheets 30 constituting the rotor core 7. The connection passage 60 is formed by axially communicating the third slits 23 provided in all the first electromagnetic steel sheets 20 constituting the rotor core 7. In addition, the fourth slits 24 provided in all of the first electromagnetic steel sheets 20 constituting the rotor core 7 and the sixth slits 32 provided in the second electromagnetic steel sheets are connected in the axial direction to form an accommodating portion 70.

[0039] The upstream passage 40 includes a plurality of first upstream passages 41 and a plurality of second upstream passages 42 (see FIG. 4). The first upstream passages 41 are formed by first slits 21 provided in the plurality of first electromagnetic steel sheets 20. The second upstream passages 42 are formed by second slits 22 provided in the plurality of first electromagnetic steel sheets 20.

[0040] The rotor core 7 is provided with a plurality of second inlets 43 opening on the inner circumferential surface of the rotor core 7. The second inlets 43 are provided at positions facing the first outlets 5d of the shaft 2. In this embodiment, the second inlets 43 are provided at 16 locations, and are provided every 22.5 degrees in the circumferential direction on the inner circumferential surface of the rotor core 7.

[0041] The plurality of first upstream passages 41 and second upstream passages 42 are provided so as to extend radially outward from the corresponding second inlets 43, respectively.

[0042] The first upstream passages 41 and the second upstream passages 42 are provided alternately in the circumferential direction. In this embodiment, the first upstream passages 41 extend along the q-axis direction. The second upstream passages 42 extend along the d-axis direction. In this embodiment, the d-axis direction is the central axis direction of the magnetic poles of the permanent magnets 8, and the q-axis direction is the central axis direction between the magnetic poles of the permanent magnets 8 adjacent to each other in the circumferential direction of the rotor 3.

[0043] Further, the first upstream passages 41 and the second upstream passages 42 are configured to have a generally mushroom-shaped axial cross section. In other words, the outer circumferential portions of the first upstream passages 41 and the second upstream passages 42 are larger in circumferential dimension than the inner circumferential portions of the first upstream passages 41 and the second upstream passages 42. In this embodiment, the outer circumferential portions of the first upstream passages 41 and the second upstream passages 42 are configured to have an elliptical axial cross section.

[0044] In FIG. 4, when the shaft 2 is viewed in the d-axis direction and the q-axis direction, the mediums present at the circumferential positions corresponding to the respective directions are different. At the circumferential position corresponding to the d-axis direction, there are an air gap (second upstream passage 42) region and an electromagnetic steel sheet (first electromagnetic steel sheet 20) region from the radial inner side to the radial outer side, in that order. On the other hand, at the circumferential position corresponding to the q-axis direction, there are an air gap (first upstream passage 41) region, an electromagnetic steel sheet (first electromagnetic steel sheet 20) region, an air gap (connection passage 60) region, and an electromagnetic steel sheet (first electromagnetic steel sheet 20) region from the radial inner side to the radial outer side, in that order. Therefore, at the circumferential position corresponding to the q-axis direction, the proportion of the electromagnetic steel sheet is smaller than that at the circumferential position corresponding to the d-axis direction. The smaller the proportion of the electromagnetic steel sheet, in other words, the greater the proportion of the air gap, the more likely the mechanical properties in the radial direction (for example, mechanical strength against the centrifugal force generated when the rotor 3 rotates) are to be reduced. 4, the circumferential distance between the d-axis and the nearest gap (accommodating portion 70) in the rotor 3 is shorter than the circumferential distance between the q-axis and the nearest gap (accommodating portion 70). Here, the shorter the circumferential distance from each axis (d-axis, q-axis) to the nearest gap (accommodating portion 70), the more likely the mechanical properties in the radial direction are to be reduced. Note that the present embodiment shown in FIG. 4 illustrates an example in which the mechanical properties in the radial direction are lower at the circumferential position corresponding to the d-axis direction in the rotor 3 than at the circumferential position corresponding to the q-axis direction.

[0045] 4, the radial distance between the first upstream passage 41 and the connecting passage 60 at a circumferential position in the rotor 3 that generally corresponds to the q axis direction is shorter than the radial distance between the second upstream passage 42 and the accommodating portion 70 at a circumferential position that generally corresponds to the d axis direction. As a result, the portion between the first upstream passage 41 and the connecting passage 60 in the radial direction of the rotor 3 has lower mechanical properties in the circumferential direction of the rotor 3 than the portion between the second upstream passage 42 and the accommodating portion 70.

[0046] When the rotor 3 rotates, the centrifugal force generated by the rotation of the rotor 3 causes the rotor 3 to deform in a circumferential position where the mechanical properties in the radial direction are relatively low so as to extend radially outward compared to other parts. In this embodiment, the circumferential position corresponding to the d-axis direction in the rotor 3 has lower mechanical properties in the radial direction than the circumferential position corresponding to the q-axis direction, so the rotor 3 deforms in a circumferential position where the d-axis direction in the rotor 3 extends radially outward compared to the circumferential position corresponding to the q-axis direction in the rotor 3. As a result of this deformation, stress is generated in the circumferential direction in the middle part of the rotor 3 (the part between the first upstream passage 41 and the connection passage 60 and the part between the second upstream passage 42 and the accommodating section 70). In contrast, in this embodiment, the first radial position R1 of the outer circumferential end of the first upstream passage 41 is set radially inward from the second radial position R2 of the outer circumferential end of the second upstream passage 42. In this way, the radial distance between the first upstream passage 41 and the connecting passage 60 is longer than when the first radial position R1 is set to the same radial position as the second radial position R2. As a result, the portion between the first upstream passage 41 and the connecting passage 60 has high mechanical properties in the circumferential direction of the rotor 3, and is therefore less likely to deform so as to extend in the circumferential direction. In other words, it is possible to reduce the difference in the mechanical properties in the circumferential direction of the rotor 3 that differs depending on the circumferential position of the rotor 3 (for example, the difference in the mechanical properties in the circumferential direction between the circumferential position in the rotor 3 that corresponds approximately to the d-axis direction and the circumferential position in the rotor 3 that corresponds approximately to the q-axis direction) compared to the conventional method. As a result, it is possible to prevent the occurrence of a portion in the rotor 3 that has relatively low mechanical properties in the circumferential direction. This makes it possible to prevent the occurrence of local stress concentration due to centrifugal force during rotation of the rotor 3 in the portion with relatively low mechanical properties in the circumferential direction, which would affect the reliability of the rotor 3.

[0047] Furthermore, by setting the first radial position R1 of the outer circumferential end of the first upstream passage 41 radially inward from the second radial position R2 of the outer circumferential end of the second upstream passage 42, it becomes easier to increase R of the outer circumferential end of the first upstream passage 41. This makes it possible, for example, to disperse stress acting on the outer circumferential portion of the first upstream passage 41 when the rotor 3 rotates.

[0048] In the present embodiment, the second radial position R2 of the outer circumferential end of the second upstream passage 42 is set radially outward from the first radial position R1 of the outer circumferential end of the first upstream passage 41. In this manner, the radial distance between the second upstream passage 42 and the accommodating portion 70 at a circumferential position substantially corresponding to the d-axis direction is shorter than when the second radial position R2 is set at the same radial position as the first radial position R1. As a result, the portion between the second upstream passage 42 and the accommodating portion 70 has low mechanical properties in the circumferential direction of the rotor 3, and therefore it is possible to alleviate the stress acting on the portion between the first upstream passage 41 and the connecting passage 60.

[0049] As shown in FIG. 1, the downstream passage 50 includes a first downstream passage 51 provided on one axial side of the upstream passage 40, and a second downstream passage 52 provided on the other axial side of the upstream passage 40.

[0050] The first downstream passage 51 is formed by stacking the second electromagnetic steel sheets 30 in the axial direction so that the fifth slits 31 of all the second electromagnetic steel sheets 30 located on one axial side of the first electromagnetic steel sheet 20 are connected in the axial direction.

[0051] The second downstream passage 52 is formed by stacking the second electromagnetic steel sheets 30 in the axial direction so that the fifth slits 31 of all the second electromagnetic steel sheets 30 located on the other axial side of the first electromagnetic steel sheet 20 are connected in the axial direction.

[0052] The other axial end of the first downstream passage 51 and one axial end of the second downstream passage 52 are connected to the outer circumferential portion of the upstream passage 40 (the first upstream passage 41 and the second upstream passage 42). In other words, the outer circumferential portion of the upstream passage 40 is connected to the first downstream passage 51 at one axial side portion, and is connected to the second downstream passage 52 at the other axial side portion.

[0053] In this embodiment, the rotor core 7 includes two types of second electromagnetic steel sheets 30 with the fifth slits 31 at different radial positions. The second electromagnetic steel sheet 30 with the fifth slits 31 provided relatively radially inward is disposed on the first electromagnetic steel sheet 20 side (axial center side), while the second electromagnetic steel sheet 30 with the fifth slits 31 provided relatively radially outward is disposed on the end plate 9 side (axial end side). As a result, the first downstream passage 51 and the second downstream passage 52 are configured to have a stepped shape in vertical cross section. In other words, the downstream parts (end plate 9 side parts) of the first downstream passage 51 and the second downstream passage 52 are located radially outward from the upstream parts (first electromagnetic steel sheet 20 side parts).

[0054] The other axial end of the first downstream passage 51 and one axial end of the second downstream passage 52 are connected via a connecting passage 60 provided radially outside the upstream passage 40. In other words, the connecting passage 60 is connected to the first downstream passage 51 at one axial side portion, and is connected to the second downstream passage 52 at the other axial side portion. In this embodiment, the first downstream passage 51, the second downstream passage 52, and the connecting passage 60 are provided radially inward of a main path (not shown) of the magnetic flux generated by the rotor 3 and the stator 4. This makes it possible to suppress interference between the main magnetic flux component (not shown) and the first downstream passage 51, the second downstream passage 52, and the connecting passage 60, and therefore prevents a decrease in output of the rotating electric machine 1 due to the provision of passages such as the first downstream passage 51.

[0055] 5, in this embodiment, one downstream passage 50 (FIG. 5 shows an example of a first downstream passage 51) is connected to one first upstream passage 41 and two second upstream passages 42 formed adjacent to each other on both circumferential sides of the first upstream passage 41. As a result, cooling oil from the three upstream passages 40 flows into one downstream passage 50.

[0056] As shown in FIG. 1, a second outlet 7b is provided at one axial end of the first downstream passage 51 and the other axial end of the second downstream passage 52, respectively.

[0057] A plurality of radially extending outflow passages 9a are arranged in parallel at predetermined intervals in the circumferential direction in the end plate 9. In this embodiment, the outflow passages 9a are recessed in a direction away from the rotor core 7 in the axial direction in the surface of the end plate 9 facing the rotor core 7.

[0058] A third inlet 9b is provided at a position facing the second outlet 7b at the inner circumferential end of the outlet passage 9a. In other words, the second outlet 7b of the downstream passage 50 and the third inlet 9b of the outlet passage 9a are connected to each other.

[0059] Further, a third outlet 9c is provided at the outer peripheral end of the outlet passage 9a. The coil end 4a of the stator 4 is disposed radially outward of the third outlet 9c at a predetermined radial distance from the third outlet 9c. In other words, the third outlet 9c faces the coil end 4a. In this embodiment, the third outlets 9c are provided at 45° intervals in the circumferential direction on the outer peripheral surface of the rotor core 7.

[0060] The accommodating portion 70 is formed by axially connecting the fourth slits 24 provided in all of the first electromagnetic steel sheets 20 and the sixth slits 32 provided in all of the second electromagnetic steel sheets 30 that constitute the rotor core 7.

[0061] Further, the housing portion 70 houses permanent magnets 8 extending in the axial direction. In this embodiment, the permanent magnets 8 housed in the housing portion 70 are arranged in a two-layer V-shape when viewed in the axial direction (see FIGS. 4 and 5).

[0062] Next, the flow of cooling oil when the rotating electric machine 1 (shaft 2 and rotor 3) is rotating (for example, during power running or regeneration) will be described with reference to FIG.

[0063] First, the cooling oil stored in an oil reservoir (not shown) is supplied to the first shaft passage 5a of the shaft 2 by the oil pump 6. Thereafter, the cooling oil in the first shaft passage 5a flows into the upstream passages 40 (the first upstream passage 41 and the second upstream passage 42) of the rotor core 7 via the second shaft passage 5b due to the centrifugal force generated by the rotation of the shaft 2 and the rotor 3 (see FIG. 4).

[0064] Next, the cooling oil that has flowed into the upstream passage 40 flows radially outward within the upstream passage 40 to its outer periphery due to centrifugal force generated by the rotation of the shaft 2 and the rotor 3. Thereafter, the cooling oil that has reached the outer periphery of the upstream passage 40 flows into the downstream passage 50 that is connected to the outer periphery of the upstream passage 40.

[0065] In this embodiment, the cooling oil in the upstream passage 40 flows into a first downstream passage 51 provided on one axial side of the upstream passage 40 and a second downstream passage 52 provided on the other axial side of the upstream passage 40. Here, the first downstream passage 51 and the second downstream passage 52 are connected via a connection passage 60. This allows the cooling oil in the first downstream passage 51 to flow into the second downstream passage 52 via the connection passage 60, and the cooling oil in the second downstream passage 52 to flow into the first downstream passage 51 via the connection passage 60. Therefore, the connection passage 60 makes it possible to balance the amount of cooling oil flowing through the first downstream passage 51 and the amount of cooling oil flowing through the second downstream passage 52.

[0066] The cooling oil that has flowed into the downstream passage 50 flows in the axial direction inside the downstream passage 50 and then flows into the outflow passage 9a. Here, the downstream passage 50 is provided so as to extend in the axial direction along the accommodating portion 70 on the radial inner side of the accommodating portion 70. As a result, when the cooling oil flows through the downstream passage 50, the radial inner portion of the accommodating portion 70 in the rotor core 7 is cooled. When this radial inner portion is cooled, the permanent magnets 8 accommodated in the accommodating portion 70 are cooled from the radial inner side, so that it is possible to suppress, for example, the temperature of the permanent magnets 8 from rising to a temperature at which irreversible demagnetization may occur.

[0067] The cooling oil that has flowed into the outlet passage 9a flows radially outward in the outlet passage 9a due to the centrifugal force caused by the rotation of the shaft 2 and the rotor 3, and then flows out radially outward from the third outlet 9c. Here, since the third outlet 9c faces the coil end 4a, the cooling oil that has flowed out from the third outlet 9c is applied (supplied) to the coil end 4a. This allows the cooling oil used to cool the permanent magnet 8 to be used to cool the coil end 4a as well. In addition, since the third outlet 9c is provided at predetermined intervals in the circumferential direction (in this embodiment, a total of eight outlets are provided at 45 degree intervals), it is possible to apply the cooling oil that has flowed out from the third outlet 9c over the entire coil end 4a. This allows the cooling oil to be applied differently depending on the circumferential position of the coil end 4a, that is, it is possible to suppress the occurrence of a temperature distribution in the circumferential direction.

[0068] As described above, according to this embodiment, the permanent magnets 8 can be cooled by the cooling oil that flows from the shaft passage 5 into the rotor passages (the upstream passage 40 and the downstream passage 50). In addition, by making the first radial position R1 of the outer circumferential end of the first upstream passage 41 and the second radial position R2 of the outer circumferential end of the second upstream passage 42 different from each other, it is possible to reduce the difference in the mechanical characteristics of the rotor 3 that differs depending on the circumferential position compared to the conventional art. As a result, even if local stress concentration occurs due to centrifugal force when the rotor 3 rotates, it is possible to suppress the reliability of the rotor 3 from being adversely affected.

[0069] Furthermore, by making the first radial position R1 of the outer circumferential end of the first upstream passage 41 extending along the q-axis direction different from the second radial position R2 of the outer circumferential end of the second upstream passage 42 extending along the d-axis direction, it is possible to reduce the difference in the mechanical characteristics of the rotor 3 that occurs between the circumferential position corresponding to the q-axis direction and the circumferential position corresponding to the d-axis direction more than in the conventional case.

[0070] Moreover, the first upstream passages 41 and the second upstream passages 42 are provided alternately in the circumferential direction of the rotor 3. This makes it possible to further reduce the difference in mechanical characteristics of the rotor 3 that differs depending on the circumferential position compared to the conventional art.

[0071] In addition, the axial cross section of the outer circumferential portion of the upstream passage 40 is elliptical. This makes the radius of curvature of the outer circumferential portion of the upstream passage 40 larger than that of a circular shape, so that it becomes possible to disperse stress acting on the outer circumferential portion of the upstream passage 40 during, for example, the rotor 3 rotations.

[0072] In addition, since the second inlet 43 is provided in the axial center portion of the rotor 3, it is possible to cool the axial center portion of the permanent magnet 8, which is likely to become hotter, in preference to other portions, by using the cooling oil flowing from the shaft passage 5 into the upstream passage 40. This makes it possible to prevent the axial center portion of the permanent magnet 8 from becoming hot. In addition, the radial position of the outer circumferential end of the first upstream passage 41 provided on the radial inside of the connection passage 60 is set radially inside the radial position of the outer circumferential end of the second upstream passage 42. This makes it possible to relatively reduce the proportion of the first upstream passage 41 (gap) in the circumferential position where the connection passage 60 is provided, and therefore makes it possible to reduce the difference in mechanical characteristics of the rotor 3 that occurs between the circumferential position where the first upstream passage 41 and the connection passage 60 are provided and the circumferential position where the second upstream passage 42 is provided.

[0073] Furthermore, the cooling oil used to cool the permanent magnets 8 when passing through the downstream passage 50 flows out from the third outlet 9c and is supplied to the coil ends 4a. This allows the cooling oil after cooling the permanent magnets 8 to also be used to cool the coil ends 4a.

[0074] Moreover, since the rotor 3 and the shaft 2 are fixed by shrink fitting, the rotor 3 and the shaft 2 can be reliably fixed. Moreover, the upstream passage 40 extending radially outward from the second inlet 43 opening on the inner peripheral surface of the rotor 3 can relieve shrink fitting stress acting on the rotor 3. This can further improve the reliability of the rotor 3.

[0075] In addition, by positioning the upstream portions of the first downstream passage 51 and the second downstream passage 52 radially inward from the respective downstream portions, it is possible to position the outer circumferential ends of the upstream passages connected to the first downstream passage 51 and the second downstream passage 52 radially inward. This makes it possible to suppress deterioration of the mechanical characteristics of the rotor 3 due to the upstream passage 40 becoming longer in the radial direction. Furthermore, by positioning the downstream portions of the first downstream passage 51 and the second downstream passage 52 radially outward from the respective upstream portions, the downstream portions come closer to the permanent magnets 8 in the radial direction, so that it is possible to further improve the cooling performance of the permanent magnets 8 by the cooling oil flowing through the first downstream passage 51 and the second downstream passage 52.

[0076] In addition, since the first downstream passage 51 and the second downstream passage 52 are connected by the connecting passage 60, it is possible to reduce the difference between the amount of cooling oil flowing through the first downstream passage 51 and the amount of cooling oil flowing through the second downstream passage 52.

[0077] In this embodiment, the rotating electric machine 1 is described as an electric motor, but it may be used as a generator. Also, the rotating electric machine 1 may be used for purposes other than a drive source for running an electric vehicle.

[0078] Furthermore, in this embodiment, the rotating electric machine 1 has been described as being of an embedded magnet type, but it may also be of a surface magnet type.

[0079] Furthermore, in this embodiment, the rotor core 7 is formed by laminating a plurality of electromagnetic steel plates, but it may be formed from a single part such as a casting.

[0080] Furthermore, in this embodiment, the permanent magnets 8 are arranged in a V-shape when viewed in the axial direction, but may be arranged in a shape other than a V-shape (for example, a V-shape).

[0081] In the present embodiment, the radial position of the outer peripheral end of the second upstream passage 42 is set at a position radially outward from the radial position of the outer peripheral end of the first upstream passage 41. However, the radial position of the outer peripheral end of the second upstream passage 42 may be set at a position radially inward from the radial position of the outer peripheral end of the first upstream passage 41. In this way, for example, it is possible to reduce the difference in the mechanical characteristics of the rotor 3 in the radial direction, which differs depending on the circumferential position, compared to the conventional art. In more detail, the more the outer peripheral end of the upstream passage 40 is located radially outward, the greater the proportion of the upstream passage 40 in the circumferential position of the rotor core 7, so that the mechanical characteristics in the radial direction of the circumferential position are relatively low. On the other hand, the more the outer peripheral end of the upstream passage 40 is located radially inward, the smaller the proportion of the upstream passage 40 in the circumferential position of the rotor core 7, so that the mechanical characteristics in the radial direction of the circumferential position are relatively high. Therefore, at a circumferential position where the radial mechanical properties of the rotor core 7 are relatively low, the radial position of the outer circumferential end of the second upstream passage 42 is set relatively to the inner circumferential side (radially inside) to reduce the proportion of the second upstream passage 42 (gap), that is, to increase the proportion of the electromagnetic steel sheet, thereby increasing the radial mechanical properties of the circumferential position. On the other hand, at a circumferential position where the radial mechanical properties of the rotor core 7 are relatively high, the radial position of the outer circumferential end of the first upstream passage 41 is set relatively to the outer circumferential side (radially outside) to increase the proportion of the second upstream passage 42 (gap), that is, to decrease the proportion of the electromagnetic steel sheet, thereby making it possible to lower the radial mechanical properties of the circumferential position. In this way, by adjusting the radial positions of the outer circumferential ends of the first upstream passage 41 and the second upstream passage 42, it is possible to suppress the occurrence of variations in the radial mechanical properties between the circumferential positions of the rotor core 7.

[0082] Furthermore, in the present embodiment, the first upstream passage 41 extends along the q-axis direction, and the second upstream passage 42 extends along the d-axis direction; however, the first upstream passage 41 may extend along the d-axis direction, and the second upstream passage 42 may extend along the q-axis direction.

[0083] In the present embodiment, the radial position of the outer peripheral end of the first upstream passage 41 is set radially inward from the radial position of the outer peripheral end of the second upstream passage 42, taking into consideration the difference in the mechanical properties in the circumferential direction according to the circumferential position of the rotor 3, but the radial position of the outer peripheral end of each upstream passage 40 may be set so that the difference in at least one of the mechanical properties in the radial direction and the circumferential direction according to the circumferential position is reduced, taking into consideration various factors that cause the difference in at least one of the mechanical properties in the radial direction and the circumferential direction according to the circumferential position of the rotor 3. The factors include, for example, the presence or absence, size, material, and shape of the gap region, the electromagnetic steel plate region, and the permanent magnet 8 region in the rotor 3, the radial distance between each axis (d-axis, q-axis) and the gap, the circumferential distance between adjacent gaps, and the radial distance between adjacent gaps, but are not limited to these.

[0084] In addition, in this embodiment, the first upstream passages 41 and the second upstream passages 42 are arranged alternately in the circumferential direction of the rotor 3, but they do not have to be arranged alternately. For example, the first upstream passages 41 may be arranged so as to be continuously lined up in the circumferential direction.

[0085] In addition, in this embodiment, the outer circumferential portion of the upstream passage 40 (the first upstream passage 41 and the second upstream passage 42) is configured to have an elliptical axial cross section, but the axial cross section may be a shape other than an ellipse (for example, a circular shape).

[0086] In addition, in this embodiment, the second inlet 43 is provided in the central portion in the axial direction of the rotor 3, but it may be provided in a portion other than the central portion.

[0087] In addition, in this embodiment, the first downstream passage 51 and the second downstream passage 52 are provided, but only one of them may be provided.

[0088] Furthermore, in this embodiment, the first downstream passage 51 and the second downstream passage 52 are configured to have a stepped radial cross section so that their respective downstream portions are positioned radially outward relative to their respective upstream portions; however, the first downstream passage 51 and the second downstream passage 52 may be configured to be positioned radially outward as they proceed downstream, or the first downstream passage 51 and the second downstream passage 52 may be configured to be positioned radially inward as they proceed downstream, or the first downstream passage 51 and the second downstream passage 52 may be configured so that their radial positions do not change as they proceed downstream.

[0089] In addition, in this embodiment, the connecting passage 60 that connects the first upstream passage 41 and the second upstream passage 42 is provided, but the connecting passage 60 does not necessarily have to be provided.

[0090] In addition, in this embodiment, the cooling oil flowing out of the outflow passage 9a is configured to be applied to the coil end 4a, but the outflow passage 9a may also be configured so that the cooling oil is applied to locations other than the coil end 4a that require cooling or lubrication.

[0091] In addition, although the outflow passage 9a is provided in this embodiment, the outflow passage 9a may not be provided. In this case, for example, the cooling oil in the first downstream passage 51 and the second downstream passage 52 may be caused to flow out in the axial direction through a hole (not shown) formed so as to penetrate the end plate 9 in the thickness direction (axial direction).

[0092] In addition, in this embodiment, the shaft 2 and the rotor 3 are fixed by shrink fitting, but as long as the relative rotation between the shaft 2 and the rotor 3 can be regulated, the shaft 2 and the rotor 3 may be fixed by means other than shrink fitting, or the shaft 2 and the rotor 3 may be formed integrally.

[0093] Furthermore, in the present embodiment, an example has been described in which cooling oil is used as the liquid refrigerant, but a liquid refrigerant other than cooling oil (for example, cooling water) may be used. [Industrial Applicability]

[0094] The present invention is suitable for a rotating electric machine that can be used as a drive source for an electric vehicle, for example. [Explanation of symbols]

[0095] 1 Rotating Electric Machine 2 Shaft 3 Rotor 4 Stator 4a Coil end 5. Shaft passage 8. Permanent Magnets 9 End Plate 9a Outflow passage 9c 3rd outlet (outlet) 40 Upstream passage (inner rotor passage) 41 First upstream passage 42 2nd upstream passage 43 2nd inlet (inlet) 50 Downstream passage (inner rotor passage)

Claims

1. A rotating electric machine, A rotor having a permanent magnet; a shaft that rotatably supports the rotor; A shaft passage provided inside the shaft; a rotor passage into which a liquid refrigerant flows from the shaft passage through an inlet opening on an inner circumferential surface of the rotor, the rotor internal passage includes an upstream passage extending radially outward from the inlet, and a downstream passage connected to the upstream passage and extending in the axial direction, the upstream passage includes a first upstream passage and a second upstream passage arranged in a circumferential direction of the rotor, A rotating electric machine in which a radial position of an outer circumferential end of the first upstream passage is set at a position radially outer or inner than a radial position of an outer circumferential end of the second upstream passage.

2. 2. The rotating electric machine according to claim 1, The first upstream passage extends along the q axis direction, The second upstream passage extends along the d-axis direction.

3. 3. The rotating electric machine according to claim 1, The first upstream passages and the second upstream passages are provided alternately in a circumferential direction of the rotor.

4. 3. The rotating electric machine according to claim 1, The outer circumferential portion of the upstream passage has an elliptical axial cross section.

5. 3. The rotating electric machine according to claim 1, The inlet is provided in an axial center portion of the rotor, the downstream passage includes a first downstream passage provided on one axial side of the upstream passage and a second downstream passage provided on the other axial side of the upstream passage, a radial position of an outer circumferential end of the first upstream passage is set to a position radially inward relative to a radial position of an outer circumferential end of the second upstream passage, A connecting passage is provided radially outward of the first upstream passage, extending in the axial direction and connecting the first downstream passage and the second downstream passage.

6. 3. The rotating electric machine according to claim 1, A stator provided on the radially outer side of the rotor; A coil end provided at an axial end of the stator; an end plate provided at an axial end of the rotor; an outflow passage provided in the end plate and extending in a radial direction; The outlet passage has an inner circumferential portion connected to the downstream passage, and an outlet port provided at an outer circumferential end faces the coil end.

7. 3. The rotating electric machine according to claim 1, The rotor and the shaft are fixed to each other by shrink fitting.

Images