JP2012223075A - Cooling structure of rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure of a rotary electric machine which uniformly cools a rotor core.SOLUTION: A cooling structure of a motor generator 10 includes a rotor 20 having: a rotor core 21 where through holes 41 penetrating in the axial direction of a center shaft 101 are formed and oil passages 42, allowing an oil to be circulated therein, are respectively formed in the through holes 41; and permanent magnets 27 provided at the rotor core 21. Each through hole 41 is formed so that a cross section area S of the oil passage 42 becomes larger on the downstream side of the oil flow than on the upstream side.

Description

  The present invention generally relates to a cooling structure for a rotating electrical machine, and more particularly to a cooling structure for a rotating electrical machine in which a refrigerant passage for allowing a coolant to flow through a rotor core is formed.

  Regarding a conventional rotating electrical machine cooling structure, for example, Japanese Utility Model Laid-Open No. 6-48355 discloses a rotor of a rotating electrical machine intended to improve the cooling efficiency of the rotor (Patent Document 1). In the rotor of the rotating electrical machine disclosed in Patent Document 1, the rotor iron core is formed with an air hole extending obliquely with respect to the rotor shaft.

  Japanese Unexamined Patent Application Publication No. 2009-273284 discloses a motor intended to efficiently cool a motor including a stator core (Patent Document 2). In the motor disclosed in Patent Document 2, a coolant channel for circulating coolant through end plates disposed at both ends of the rotor core, and a coolant flowing through the coolant channel toward the coil end. A coolant outlet for jetting is formed.

Japanese Utility Model Publication No. 6-48355 JP 2009-273284 A

  As disclosed in Patent Document 1 described above, in order to cool a rotor core that generates heat as the rotor rotates, a structure in which a coolant passage extending in the rotation axis direction of the rotor is formed in the rotor core is used. However, when the refrigerant is circulated through the thus formed refrigerant passage, the temperature of the refrigerant gradually rises due to heat received from the rotor core. As a result, there is a concern that the cooling capacity of the refrigerant is reduced on the downstream side of the upstream side of the refrigerant flow, and the rotor core cannot be uniformly cooled.

  Accordingly, an object of the present invention is to solve the above-described problem and to provide a cooling structure for a rotating electrical machine in which a rotor core is cooled more uniformly.

  A cooling structure for a rotating electrical machine according to the present invention includes a rotor core that has a through-hole penetrating in the direction of the rotation axis, forms a refrigerant passage through which the refrigerant flows, and a magnet provided in the rotor core. A rotor is provided. The through hole is formed so that the cross-sectional area of the refrigerant passage is larger on the downstream side than on the upstream side of the refrigerant flow.

  According to the cooling structure of the rotating electric machine configured as described above, the through hole is formed so that the cross-sectional area of the refrigerant passage is larger on the downstream side than on the upstream side of the refrigerant flow, and thus flows in the refrigerant passage. The contact area between the refrigerant and the rotor core is larger on the downstream side than on the upstream side of the refrigerant flow. Accordingly, heat exchange between the refrigerant and the rotor core can be promoted on the downstream side of the refrigerant flow in which the refrigerant temperature tends to rise due to heat received from the rotor core. As a result, the rotor core that has become high temperature due to the heat generated by the magnet can be cooled more uniformly.

  Preferably, the rotating electrical machine cooling structure further includes a stator having a stator core disposed on the outer periphery of the rotor core and a coil wound around the stator core. The coil includes a coil end portion protruding from an end surface of the stator core in the rotation axis direction of the rotor. The refrigerant passage extends while being inclined with respect to the rotation axis of the rotor so that the refrigerant discharged from the rotor is directed to the coil end portion.

  According to the cooling structure of the rotating electric machine configured as described above, the coil end portion can be cooled using the refrigerant after cooling the rotor core.

  Preferably, the magnet is embedded in the rotor core and extends in the direction of the rotation axis of the rotor. According to the cooling structure of the rotating electrical machine configured as described above, the rotor core that has become high temperature due to the heat generated by the magnet can be uniformly cooled in the direction of the rotation axis of the rotor.

  Preferably, the through hole is formed such that the distance between the refrigerant passage and the magnet is smaller on the downstream side than on the upstream side of the refrigerant flow. According to the cooling structure of the rotating electric machine configured as described above, the refrigerant passage and the magnet as the heat source are closer to each other on the downstream side than the upstream side of the refrigerant flow. As a result, heat exchange between the refrigerant and the rotor core can be further promoted on the downstream side of the refrigerant flow, and the rotor core can be cooled more uniformly.

  As described above, according to the present invention, it is possible to provide a cooling structure for a rotating electrical machine in which the rotor core is cooled more uniformly.

It is sectional drawing which represents typically the drive unit for vehicles to which the cooling structure of the motor generator in Embodiment 1 of this invention was applied. It is sectional drawing which shows the motor generator along the II-II line in FIG. It is sectional drawing which shows the motor generator along the III-III line in FIG. It is sectional drawing which shows the motor generator along the IV-IV line in FIG. FIG. 2 is an end view showing the motor generator viewed from a direction indicated by an arrow V in FIG. 1. It is sectional drawing which shows the cooling structure of the motor generator in Embodiment 2 of this invention. It is sectional drawing which shows the motor generator along the VII-VII line in FIG. It is sectional drawing which shows the motor generator along the VIII-VIII line in FIG.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing a vehicle drive unit to which a motor generator cooling structure according to Embodiment 1 of the present invention is applied. The vehicle drive unit shown in the figure is provided in a hybrid vehicle using an internal combustion engine such as a gasoline engine or a diesel engine and a motor that receives power supply from a chargeable / dischargeable secondary battery (battery) as a power source. .

  Referring to FIG. 1, the vehicle drive unit has a motor generator 10. The motor generator 10 is a rotating electrical machine that functions as an electric motor or a generator in accordance with the traveling state of the hybrid vehicle.

  The motor generator 10 has a rotor 20 and a stator 30 as its components. The rotor 20 rotates around a central axis 101 that is a virtual axis. That is, the central axis 101 is the rotation axis of the rotor 20. A stator 30 is disposed on the outer periphery of the rotor 20.

  The rotor 20 includes a rotor core 21, end plates 22 and 23, and a plurality of permanent magnets 27. The rotor core 21 extends in the axial direction of the central shaft 101. The rotor core 21 is composed of a plurality of electromagnetic steel plates stacked in the axial direction of the central shaft 101. The rotor core 21 is rotatably supported by a bearing (not shown) provided at a distance in the axial direction of the central shaft 101. The rotor core 21 is connected to a speed reduction mechanism 15 that includes a plurality of gears.

  An oil pump 12 is provided at one end of the rotor core 21. The oil pump 12 is a gear-type oil pump that discharges oil as the rotor core 21 rotates. The oil discharged from the oil pump 12 is introduced into the rotor 20 in order to cool or lubricate each part of the motor generator 10.

  The means for supplying the oil to the rotor 20 is not limited to the pump as shown in the figure, for example, a mechanism for collecting the oil pumped up by the gear in the catch tank and guiding the oil to the rotor 20 by gravity. There may be.

  The rotor core 21 has an end surface 21a facing one end side in the direction in which the central axis 101 extends and an end surface 21b facing the other end side in the direction in which the central axis 101 extends. The end surface 21a and the end surface 21b each extend in a plane orthogonal to the central axis 101. The end surface 21 a and the end surface 21 b are configured by the surfaces of electromagnetic steel plates disposed at both ends in the axial direction of the central axis 101.

  The end plate 22 and the end plate 23 have a disk shape centered on the central axis 101. The end plate 22 is provided so as to be in contact with the end surface 21a, and the end plate 23 is provided so as to be in contact with the end surface 21b. The end plate 22 and the end plate 23 are provided so as to sandwich the rotor core 21 from both sides in the axial direction of the central shaft 101. The end plate 22 and the end plate 23 are provided to integrally hold a plurality of electromagnetic steel plates constituting the rotor core 21. The end plate 22 has an end surface 22a facing one end in the direction in which the central axis 101 extends, and the end plate 23 has an end surface 23b facing the other end in the direction in which the central axis 101 extends.

  FIG. 2 is a cross-sectional view showing the motor generator along the line II-II in FIG. In the figure, a cross section of the motor generator in the range of 90 ° in the circumferential direction around the central axis 101 is shown.

  With reference to FIGS. 1 and 2, the plurality of permanent magnets 27 are provided on the rotor core 21. In the present embodiment, the permanent magnet 27 is embedded in the rotor core 21. The permanent magnet 27 is provided extending in the axial direction of the central shaft 101.

  More specifically, the rotor core 21 is formed with a plurality of magnet insertion holes 28. Magnet insertion hole 28 penetrates rotor core 21 so as to open to end surface 21a and end surface 21b. The magnet insertion hole 28 extends in the axial direction of the central shaft 101. The plurality of magnet insertion holes 28 are formed at intervals from each other in the circumferential direction around the central axis 101. The plurality of permanent magnets 27 are embedded in the rotor core 21 by being inserted into the plurality of magnet insertion holes 28 respectively.

  As described above, the rotor 20 is an IPM (Interior Permanent Magnet) type rotor in which the permanent magnet 27 is embedded in the rotor core 21, but the present invention is not limited to this, and a magnet is attached to the surface of the rotor core. An SPM (surface permanent magnet) type rotor may be used. In addition, the rotor core 21 is not limited to an electromagnetic steel plate, and may be composed of a dust core.

  The stator 30 has a stator core 36 and a coil 37. The stator core 36 has a shape extending in a cylindrical shape in the axial direction of the central shaft 101. The stator core 36 is disposed on the outer periphery of the rotor core 21 with a minute gap between the stator core 36 and the rotor core 21. The stator core 36 is composed of a plurality of electromagnetic steel plates stacked in the axial direction of the central shaft 101. The stator core 36 has an end surface 36a facing one end in the direction in which the central axis 101 extends, and an end surface 36b facing the other end in the direction in which the central axis 101 extends. The end surface 21a and the end surface 36a are disposed so as to extend on substantially the same plane, and the end surface 21b and the end surface 36b are disposed so as to extend on substantially the same plane.

  The coil 37 is wound around the stator core 36. The coil 37 is made of, for example, a copper wire with an insulating coating. The coil 37 has a coil end portion 37P and a coil end portion 37Q. The coil end portion 37P and the coil end portion 37Q are formed so as to protrude in the axial direction of the central axis 101 from the end surface 36a and the end surface 36b, respectively. When viewed from the axial direction of the central shaft 101, the coil end portion 37P and the coil end portion 37Q are provided on the end surface 36a and the end surface 36b, respectively, so as to circulate annularly around the central shaft 101.

  The coil 37 includes a U-phase, V-phase, and W-phase coil. Each of these phase coils is electrically connected to the battery 14 via the inverter 13. The inverter 13 converts the direct current from the battery 14 into an alternating current for driving the motor, and converts the alternating current generated by the regenerative brake into a direct current for charging the battery 14.

  The power output from the motor generator 10 is transmitted from the speed reduction mechanism 15 to the drive shaft receiving portion 17 via the differential mechanism 16. The power transmitted to the drive shaft receiving portion 17 is transmitted as a rotational force to a wheel (not shown) via the drive shaft.

  On the other hand, during regenerative braking of the hybrid vehicle, the wheels are rotated by the inertial force of the vehicle body. The motor generator 10 is driven through the drive shaft receiving portion 17, the differential mechanism 16 and the speed reduction mechanism 15 by the rotational force from the wheels. At this time, the motor generator 10 operates as a generator. The electric power generated by the motor generator 10 is stored in the battery 14 via the inverter 13.

  FIG. 3 is a cross-sectional view showing the motor generator along the line III-III in FIG. 1. FIG. 4 is a cross-sectional view showing the motor generator along the line IV-IV in FIG.

  With reference to FIGS. 1 to 4, a plurality of through holes 41 are further formed in the rotor core 21.

  The through hole 41 extends along the axial direction of the central axis 101 and is formed so as to penetrate the rotor core 21. The through hole 41 is formed so as to open to the end surface 21 a and the end surface 21 b of the rotor core 21. The plurality of through holes 41 are formed at intervals from each other in the circumferential direction around the central axis 101. The through hole 41 is formed at a position corresponding to the permanent magnet 27 in the circumferential direction around the central axis 101. The through hole 41 extends along the extending direction of the permanent magnet 27 at a position adjacent to the permanent magnet 27. The through hole 41 has a circular opening shape.

  In the cooling structure of motor generator 10 in the present embodiment, oil passage 42 is formed in through hole 41. Oil as a refrigerant discharged from the oil pump 12 and introduced into the rotor 20 flows through the oil passage 42 from the end surface 21a side of the rotor core 21 toward the end surface 21b side.

  The through hole 41 is formed such that the cross-sectional area S of the oil passage 42 when the rotor core 21 is cut by a plane orthogonal to the central axis 101 is larger on the downstream side than on the upstream side of the oil flow. The through hole 41 is formed such that the cross-sectional area S of the oil passage 42 increases in the axial direction of the central shaft 101 from the end surface 21a side of the rotor core 21 toward the end surface 21b side. The through hole 41 is formed such that the cross-sectional area S of the oil passage 42 is the smallest on the end surface 21a and the largest on the end surface 21b in the axial direction of the central shaft 101. The through hole 41 is formed such that the cross-sectional area S of the oil passage 42 continuously changes in the axial direction of the central shaft 101.

  The through hole 41 has a bottom 43 and a top 44. The bottom 43 is a portion of the through hole 41 that is positioned closest to the permanent magnet 27 when the rotor core 21 is cut by an arbitrary plane orthogonal to the central axis 101. The bottom 43 is disposed on the outermost peripheral side with respect to the central axis 101 among the side walls of the through hole 41 that defines the through hole 41. The top portion 44 is a portion of the through hole 41 that is located farthest from the permanent magnet 27 when the rotor core 21 is cut by an arbitrary plane orthogonal to the central axis 101. The top portion 44 is provided at a position facing the bottom portion 43 in the radial direction about the central axis 101.

  As shown in FIGS. 3 and 4, the through hole 41 is formed so that the curvature of the side wall defining the through hole 41 in the vicinity of the bottom 43 is larger toward the upstream side of the oil flow and smaller toward the downstream side of the oil flow. Has been.

  As shown in FIG. 1, the through hole 41 has a distance L1 between the oil passage 42 and the permanent magnet 27, in other words, a distance L1 between the bottom 43 of the through hole 41 and the permanent magnet 27. It is formed to be smaller on the downstream side than on the upstream side. Further, in the present embodiment, the through hole 41 is formed such that the distance L <b> 2 between the top 44 of the through hole 41 and the permanent magnet 27 is constant in the axial direction of the central axis 101. With such a configuration, the through hole 41 as a whole extends while being inclined with respect to the axial direction of the central shaft 101.

  The through hole 41 is not limited to the above shape, and may be appropriately changed under the condition that the cross-sectional area S of the oil passage 42 is larger on the downstream side than on the upstream side of the oil flow.

  Specifically, the through hole 41 may have an opening shape other than a circle, for example, an opening shape such as a rectangle, a polygon, or an ellipse. The through hole 41 may be formed such that the cross-sectional area S of the oil passage 42 changes intermittently in the axial direction of the central shaft 101. The through hole 41 may be formed such that the distance L2 between the top portion 44 of the through hole 41 and the permanent magnet 27 is larger on the downstream side than on the upstream side of the oil flow, or may be smaller. It may be formed. The through hole 41 may be formed at a position shifted from the position corresponding to the permanent magnet 27 in the circumferential direction around the central axis 101, for example, at the center position of two permanent magnets 27 adjacent in the circumferential direction.

  As the rotor 20 rotates, the permanent magnet 27 generates heat, and the heat is transmitted to the rotor core 21. On the other hand, since the oil supplied to the rotor core 21 receives a centrifugal force generated by the rotation of the rotor 20, the oil flows through the oil passage 42 while being in contact with the bottom 43 side of the through hole 41 as shown in FIGS. . During this time, heat generated between the permanent magnet 27 is radiated by heat exchange between the oil and the rotor core 21. At this time, since the temperature of the oil gradually rises due to heat received from the rotor core 21, the cooling capacity by the oil tends to be lowered on the downstream side of the oil flow in the oil passage 42 than on the upstream side.

  In contrast, in the present embodiment, the through hole 41 is formed so that the cross-sectional area S of the oil passage 42 is larger on the downstream side than on the upstream side of the oil flow. With such a configuration, the contact area between the oil flowing through the oil passage 42 and the rotor core 21 is larger on the downstream side than on the upstream side of the oil flow, as shown in FIGS. 3 and 4 (s1 <s2 ). As a result, heat exchange between the oil and the rotor core 21 can be promoted on the downstream side of the oil flow, and a decrease in cooling capacity due to an increase in oil temperature can be compensated.

  In addition, in the present embodiment, the through hole 41 is formed such that the distance L1 between the oil passage 42 and the permanent magnet 27 is smaller on the downstream side than on the upstream side of the oil flow. With such a configuration, the heat transfer distance from the permanent magnet 27 to the oil passage 42 can be reduced toward the downstream side of the oil flow, and heat exchange between the oil and the rotor core 21 can be further promoted. In addition, since the oil flows on the bottom 43 of the through hole 41 inclined from the inner peripheral side to the outer peripheral side while receiving the centrifugal force, the oil flow rate becomes higher toward the downstream side of the oil flow. Thereby, since the frequency which takes the heat of the rotor core 21 with oil becomes high, the cooling efficiency of the rotor core 21 can be improved.

  For the above reasons, the cooling efficiency of the rotor core 21 can be improved on the downstream side of the oil flow in which the oil temperature rises, and the rotor core 21 can be uniformly cooled in the axial direction of the central shaft 101.

  FIG. 5 is an end view showing the motor generator as viewed from the direction indicated by arrow V in FIG. With reference to FIG. 1 and FIG. 5, an oil supply hole 51 and an oil discharge hole 52 are formed in the end plate 22. The oil supply hole 51 extends outward in the radial direction around the central axis 101 and communicates with the through hole 41. The oil introduced into the rotor 20 by the oil pump 12 is supplied to the oil passage 42 through the oil supply hole 51.

  The oil discharge hole 52 extends radially outward from the path of the oil supply hole 51 with the central axis 101 as the center, and opens to the end surface 22a. A coil end portion 37P is located on the extension of the opening surface of the oil discharge hole 52 in the end surface 22a. Part of the oil flowing through the oil supply hole 51 is discharged toward the coil end portion 37P through the oil discharge hole 52.

  An oil discharge hole 53 is formed in the end plate 23. The oil discharge hole 53 is formed on the extension of the through hole 41 in the axial direction of the central shaft 101 and opens to the end surface 23b. The oil discharge hole 53 forms an oil passage 42 together with the through hole 41. The oil discharge hole 53 is formed so as to increase in diameter as it approaches the end surface 23 b in the axial direction of the central shaft 101. The through hole 41 and the oil discharge hole 53 extend with an inclination with respect to the central axis 101 so that the oil discharged from the rotor 20 is directed to the coil end portion 37Q.

  With this configuration, in the present embodiment, a part of the oil before being supplied to the rotor core 21 is used to cool the coil end portion 37P and the oil after the rotor core 21 is cooled is used. The coil end portion 37Q can be cooled.

  The cooling structure for motor generator 10 according to the first embodiment of the present invention described above will be described together. The cooling structure for motor generator 10 as the rotating electrical machine according to the present embodiment is based on central shaft 101 as the rotating shaft. A through-hole 41 penetrating in the axial direction is formed, and a rotor core 21 forming an oil passage 42 as a refrigerant passage through which oil as a refrigerant flows inside the through-hole 41, and a permanent magnet as a magnet provided in the rotor core 21 27. The through hole 41 is formed such that the cross-sectional area of the oil passage 42 is larger on the downstream side than on the upstream side of the oil flow.

  According to the cooling structure for motor generator 10 according to Embodiment 1 of the present invention configured as described above, the oil passage 42 penetrates so that the cross-sectional area S is larger on the downstream side than on the upstream side of the oil flow. Since the hole 41 is formed, the rotor core 21 can be uniformly cooled in the direction of the rotation axis of the rotor 20. This eliminates the need to set the cooling capacity of the rotor core 21 with reference to the position where the temperature distribution of the rotor core 21 becomes high. As a result, the oil pump 12 can be reduced in size, and as a result, the fuel loss of the hybrid vehicle can be improved by minimizing the energy loss for oil supply.

  In the present embodiment, the case where the cooling structure for a rotating electrical machine according to the present invention is applied to a motor generator mounted on a hybrid vehicle has been described. However, the present invention is not limited to this, and a motor mounted on an electric vehicle, The present invention may be applied to various industrial motors.

(Embodiment 2)
FIG. 6 is a sectional view showing a cooling structure for a motor generator in the second embodiment of the present invention. FIG. 7 is a cross-sectional view showing the motor generator along the line VII-VII in FIG. 6. FIG. 8 is a cross-sectional view showing the motor generator along the line VIII-VIII in FIG. 6.

  Note that the motor generator cooling structure in the present embodiment is basically similar to that of motor generator 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  6 to 8, the through hole 41 is formed so that the cross-sectional area S of the oil passage 42 is larger on the downstream side than on the upstream side of the oil flow. In the present embodiment, the through hole 41 has a rectangular opening shape having a height H and a width B. The bottom 43 of the through hole 41 is formed in a step shape so as to be closer to the permanent magnet 27 from the upstream side to the downstream side of the oil flow. The top portion 44 of the through hole 41 is formed in a planar shape in the axial direction of the central axis 101 so that the distance between the top portion 44 and the permanent magnet 27 does not change. The through hole 41 is formed so that the height H and the width B are larger on the downstream side than on the upstream side of the oil flow.

  According to the motor generator cooling structure in the second embodiment of the present invention configured as described above, the effects described in the first embodiment can be obtained in the same manner.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly applied to a vehicle including a motor as a power source.

  DESCRIPTION OF SYMBOLS 10 Motor generator, 12 Oil pump, 13 Inverter, 14 Battery, 15 Reduction mechanism, 16 Differential mechanism, 17 Drive shaft receiving part, 20 Rotor, 21 Rotor core, 21a, 21b, 22a, 23b, 36a, 36b End surface, 22, 23 End plate, 27 Permanent magnet, 28 Magnet insertion hole, 30 Stator, 36 Stator core, 37 Coil, 37P, 37Q Coil end portion, 41 Through hole, 42 Oil passage, 43 Bottom portion, 44 Top portion, 51 Oil supply hole, 52, 53 Oil discharge hole, 101 central axis.

Claims (4)

A rotor having a rotor core formed with a through-hole penetrating in the direction of the rotation axis and forming a refrigerant passage through which the refrigerant flows, and a magnet provided in the rotor core;
The through hole is a cooling structure for a rotating electrical machine in which the cross-sectional area of the refrigerant passage is formed to be larger on the downstream side than on the upstream side of the refrigerant flow. A stator core disposed on the outer periphery of the rotor core, and a stator having a coil wound around the stator core;
The coil includes a coil end portion protruding from an end surface of the stator core in the rotation axis direction of the rotor,
2. The cooling structure for a rotating electrical machine according to claim 1, wherein the refrigerant passage extends while being inclined with respect to a rotation axis of the rotor such that the refrigerant discharged from the rotor moves toward the coil end portion.   The cooling structure for a rotating electrical machine according to claim 1, wherein the magnet is embedded in the rotor core and extends in a rotation axis direction of the rotor.   The cooling structure for a rotating electrical machine according to claim 3, wherein the through hole is formed such that a distance between the refrigerant passage and the magnet is smaller on the downstream side than on the upstream side of the refrigerant flow.

Images