JP2012165488A - Cooling device for rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a rotary electric machine that prevents drag torque and thus prevents a reduction in fuel efficiency.SOLUTION: A cooling device provides cooling for a rotary electric machine 100 by guiding cooling oil A into a rotatable shaft 58 and feeding the cooling oil A to a stator 50, which is arranged on an outer circumference of a rotor 10 provided fixedly around the shaft 58, by means of centrifugal force generated by rotation of the rotor 10. The cooling device has a micro-bubble generating section 22 (23) that is provided on the outer circumference of the rotor 10 and generates micro-bubbles by the rotation of the rotor 10.

Description

  The present invention relates to a cooling device for a rotating electrical machine.

  2. Description of the Related Art Conventionally, a drive device for a vehicle such as an automobile is known that includes a rotating electrical machine such as a motor or a generator. The rotating electrical machine generates heat as it operates. Since this heat generation may reduce the operating efficiency of the rotating electrical machine, it is necessary to cool the rotating electrical machine during operation.

  For example, Patent Document 1 describes a cooling device that cools a rotating electrical machine by supplying a refrigerant introduced into a shaft to a stator side by centrifugal force generated by rotation of a rotor.

JP 2009-27837 A

  However, as in Patent Document 1, in a cooling device that supplies refrigerant into a rotating electrical machine, the supplied refrigerant enters between the rotor and the stator, and drag torque is generated when the rotor rotates due to the influence of the entered refrigerant. As a result, there is a possibility that the driving efficiency is lowered and the fuel consumption is deteriorated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cooling device for a rotating electrical machine that can suppress the generation of drag torque and suppress deterioration in fuel consumption.

  According to the present invention, the refrigerant introduced into the shaft provided rotatably is supplied to the stator side disposed on the outer periphery of the rotor by centrifugal force generated by the rotation of the rotor fixed around the shaft. Then, the cooling device for cooling the rotating electrical machine includes a microbubble generator provided on the outer periphery of the rotor and generating microbubbles by the rotation of the rotor.

  The microbubble generating part is preferably a concave part formed on the outer periphery of the rotor.

  Or it is preferable that the said microbubble generation | occurrence | production part is a convex-shaped part formed on the outer periphery of the said rotor.

  The cooling device for a rotating electrical machine according to the present invention preferably includes a microbubble generator that mixes microbubbles into the refrigerant introduced into the shaft.

  The cooling device for a rotating electrical machine according to the present invention generates microbubbles along with the rotation of a rotor in a microbubble generator provided on the outer periphery of the rotor, and forms an air film on the rotor surface by the microbubbles. As a result, there is an effect that generation of drag torque can be suppressed and fuel consumption deterioration can be suppressed.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a cooling device for a rotating electrical machine according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view in which a part of the rotor shown in FIG. 1 is enlarged. FIG. 3 is a view of the rotor core as seen from the direction of the center line. FIG. 4 is an enlarged view of one of the microbubble generators shown in FIG. FIG. 5 is a view of the rotor core as seen from the direction of the center line. FIG. 6 is an enlarged view of one of the microbubble generators shown in FIG. FIG. 7 is a cross-sectional view illustrating a schematic configuration of a cooling device for a rotating electrical machine according to a second embodiment of the present invention.

  Hereinafter, embodiments of a cooling apparatus for a rotating electrical machine according to the present invention will be described in detail with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[First embodiment]
First, with reference to FIGS. 1-6, 1st embodiment of this invention is described. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a cooling device for a rotating electrical machine according to the present embodiment. The rotating electrical machine shown in the figure is a motor mounted on a hybrid vehicle that uses an internal combustion engine such as a gasoline engine or a diesel engine and a motor powered by a chargeable / dischargeable secondary battery (battery) as a power source. . The rotating electric machine means a motor generator having at least one of a function as a motor and a function as a generator (generator) when electric power is supplied.

  Referring to FIG. 1, rotating electric machine 100 includes a rotor 10 and a stator 50 disposed on the outer periphery of rotor 10. The rotor 10 is provided on a shaft 58 that extends along the center line 101. The rotor 10 is fixed around the shaft 58 and rotates about the center line 101 together with the shaft 58. The rotor 10 and the stator 50 are accommodated in a housing (not shown) that rotatably holds the shaft 58.

  The rotor 10 includes a rotor core 20 and a permanent magnet 31 embedded in the rotor core 20. That is, the rotating electrical machine 100 is an IPM (Interior Permanent Magnet) motor. The rotor core 20 has a cylindrical shape along the center line 101. The rotor core 20 is composed of a plurality of electromagnetic steel plates 21 stacked in the axial direction of the center line 101.

  An end plate 29 is provided on the axial end surface of the rotor 10 located in the direction of the center line 101.

  The stator 50 includes a stator core 55 and a coil 51 wound around the stator core 55. The stator core 55 is composed of a plurality of electromagnetic steel plates 52 stacked in the axial direction of the center line 101. Note that the rotor core 20 and the stator core 55 are not limited to electromagnetic steel plates, and may be formed of, for example, a dust core.

  The coil 51 is electrically connected to the control device 70 by a three-phase cable 60. The three-phase cable 60 includes a U-phase cable 61, a V-phase cable 62, and a W-phase cable 63. The coil 51 includes a U-phase coil, a V-phase coil, and a W-phase coil, and a U-phase cable 61, a V-phase cable 62, and a W-phase cable 63 are connected to terminals of these three coils, respectively.

  A torque command value to be output by the rotating electrical machine 100 is sent to the control device 70 from an ECU (Electrical Control Unit) 80 mounted on the hybrid vehicle. The control device 70 generates a motor control current for outputting the torque specified by the torque command value, and supplies the motor control current to the coil 51 via the three-phase cable 60.

  FIG. 2 is an enlarged cross-sectional view in which a part of the rotor 10 shown in FIG. 1 is enlarged. As shown in FIG. 2, the rotating electrical machine 100 includes a magnet cooling passage 40 that cools the permanent magnet 31 with cooling oil (refrigerant) A introduced into the shaft 58. The magnet cooling passage 40 includes a refrigerant passage 45 formed inside the shaft 58, a refrigerant passage 43 formed in the end plate 29 that communicates with the refrigerant passage 45, and a discharge hole 44 that communicates with the refrigerant passage 43. I have.

  The refrigerant passage 45 includes an axial passage 41 that extends in the direction of the center line 101, and a radial passage 42 that is connected to the axial passage 41 and extends in the radial direction of the shaft 58.

  The refrigerant passage 43 is connected to the radial passage 42 and connected to the flow path 43a extending toward the permanent magnet 31 and the outer diameter direction end of the flow path 43a, and the radial direction of the rotor 10 from the radial end. And a flow path 43b extending inward.

  Of the main surfaces 29 a to 29 d of the end plate 29, the flow path 43 a is formed by grooves formed on the main surfaces 29 c and 29 d facing the axial end surface 10 b of the rotor 10 and the axial end surfaces 10 a and 10 b of the rotor 10. It is prescribed. The flow path 43 a passes through axial end faces 31 a and 31 b located in the axial direction of the rotor core 20 in the surface of the permanent magnet 31. Thereby, the permanent magnet 31 with low heat resistance can be cooled with oil.

  In FIG. 2, the flow path 43 b is connected to the outer diameter direction end of the flow path 43 a, and extends from the outer diameter direction end of the flow path 43 a toward the radially inner side of the rotor 10. As described above, since the refrigerant passage 43 is formed long in the end plate 29, the contact area between the oil and the end plate 29 can be increased, and the end plate 29 can be cooled well. Further, it is possible to reduce the temperature rise of the magnet due to the heat generation in the end plate 29.

  The discharge hole 44 opens on the main surfaces 29 a and 29 b of the end plate 29. Oil is discharged from the discharge hole 44 to the outside.

  Next, the cooling structure of the rotating electrical machine by the cooling device of this embodiment will be described. Oil A supplied from the outside into the refrigerant passage 45 formed inside the hollow shaft 58 flows along the direction of the center line 101 inside the axial passage 41. Since the shaft 58 rotates, centrifugal force is generated, and the oil A flows along the wall surface of the axial passage 41. Due to the action of the centrifugal force, part of the oil A that has reached the radial passage 42 flows into the radial passage 42 and flows inside the radial passage 42 toward the radially outer side of the shaft 58.

  Then, the oil A flows into the refrigerant passage 43 in the end plate 29 and flows through the refrigerant passage 43, and the axial end faces 10 a and 10 b of the rotor 10, the axial end faces 31 a and 31 b of the permanent magnet 31, and The end plate 29 is cooled. Thereafter, the oil A reaches the discharge hole 44 and flows out from the discharge hole 44 to the internal space of the rotating electrical machine.

  Furthermore, since the centrifugal force generated by the rotation of the rotor 10 is acting on the oil A, the oil A is supplied from the discharge hole 44 toward the outer peripheral side (stator 50 side) of the rotor 10 by this centrifugal force. Sprayed and scattered. The oil A thus scattered reaches the inner surface 51 a in the rotational radius direction of the coil 51 of the stator 50 and cools the coil 51. As described above, the oil A introduced into the shaft 58 causes the rotor 10 (the axial end faces 10a and 10b of the rotor 10, the axial end faces 31a and 31b of the permanent magnet 31 and the end plate 29) and the stator 50 (coil 51). The rotating electrical machine 100 including is cooled.

  Here, in such a cooling structure, when oil is sprayed and scattered from the discharge hole 44 of the rotor 10 toward the stator, a part of the scattered oil enters a gap formed between the rotor 10 and the stator 50. There is. If oil enters the gap, dragging torque is generated due to the viscosity of the oil, and the rotation of the rotor is hindered. As a result, there is a possibility that the driving efficiency and fuel consumption are deteriorated.

  Therefore, in particular, in the present embodiment, in order to avoid such a situation, the microbubble generator 22 is provided on the outer periphery of the rotor 10, more specifically, on the outer peripheral surface 20a of the rotor core 20 (see FIGS. 3 and 4). Yes. The microbubble generator 22 generates microbubbles B around the rotor 10 by the rotation of the rotor 10, and specifically, a plurality of concaves formed on the outer peripheral surface 20a of the rotor 10 (rotor core 20). It is a part that forms a shape.

  FIG. 3 is a view of the rotor core 20 viewed from the direction of the center line 101, and FIG. 4 is an enlarged view of one of the microbubble generators 22 shown in FIG. As shown in FIGS. 3 and 4, the microbubble generating portion 22 is a concave-shaped portion having a triangular cross-sectional shape in the axial direction view of the rotor core 20, and more specifically, the axial direction of the rotor core 20. In view, the front portion 22a with respect to the rotational direction of the rotor 10 (rotor core 20) has a cross-sectional shape that is recessed at a substantially right angle (or acute angle) from the outer peripheral surface 20a and gently returns from the lowest point 22b to the outer peripheral surface 20a. .

  When the oil A enters between the rotor 10 and the stator 50, the microbubble generator 22 generates a negative pressure at the front portion 22 a of the microbubble generator 22 as the rotor 10 rotates. When the negative pressure is generated, the air dissolved in the oil A is expanded and deposited as microbubbles B.

  When microbubbles B are generated, oil A and microbubbles B are mixed between the rotor 10 and the stator 50. Here, since the density of the oil A is larger than that of the microbubble B, the oil A is applied with a greater centrifugal force than the microbubble B, and the oil A moves toward the stator 50 as the rotor 10 rotates. On the other hand, the microbubbles B stay on the rotor side, whereby an air film is formed on the rotor surface (the outer peripheral surface 20a of the rotor core 20).

  As a result, the rotor 10 is less likely to come into contact with the oil A that has entered between the rotor 10 and the stator 50 due to the formed air film, and is less susceptible to the influence of the oil A during rotation, so that drag torque is reduced.

  As described above, according to the cooling apparatus for a rotating electrical machine according to the present embodiment, the microbubble generator 22 is provided on the outer periphery of the rotor 10 (the outer peripheral surface 20a of the rotor core 20). The microbubbles B are generated on the outer periphery of the slab, the generation of drag torque can be suppressed, and the deterioration of fuel consumption can be suppressed. Further, the generated microbubbles B prevent oil from entering further between the rotor 10 and the stator 50.

  Moreover, since the microbubble generation part 22 is a concave-shaped part formed on the outer periphery of the rotor 10 (rotor core 20), the clearance between the rotor 10 and the stator 50 can be reduced while suppressing the generation of drag torque. As a result, the maximum generated torque is improved. Moreover, since the microbubble generation part 22 can be installed by cutting the electromagnetic steel plate 21 of the existing rotor 10, it is not necessary to provide a separate member, and cost reduction can be achieved.

  In the above-described embodiment, the concave shape of the microbubble generating portion 22 is exemplified as a triangular cross-sectional shape when viewed in the axial direction of the rotor core 20, but as long as negative pressure can be generated, a rectangular, polygonal shape can be used. Other cross-sectional shapes such as a semicircle may be used. Further, since the negative pressure increases as the outer peripheral shape of the rotor 10 changes abruptly with respect to the oil flow direction, the cross-sectional shape of the microbubble generator 22 is the front portion 22a with respect to the rotational direction of the rotor 10 (rotor core 20). In this case, it is preferable to be recessed at an acute angle or a right angle. Further, the number of the concave portions of the microbubble generator 22 may be singular or plural.

  In addition to the plurality of concave shapes along the rotation direction of the rotor 10 as described above, the shape of the microbubble generator 22 intersects the oil flow direction (rotation direction of the rotor 10) (for example, a spiral). The groove may be provided on the outer peripheral surface 20a of the rotor core 20.

  Furthermore, in the said embodiment, although the concave shape part was illustrated as a shape of a microbubble generation | occurrence | production part, as shown in FIG.5 and FIG.6, in axial direction view of the rotor core 20, each has a triangular-shaped cross section instead. It is good also as the microbubble generating part 23 which consists of a some convex-shaped part which makes a shape. When the oil flows between the rotor 10 and the stator 50, the microbubble generating unit 23 is rotated with respect to the rotation direction of the rotor 10 (rotor core 20) as the rotor rotates as shown in FIG. A negative pressure is generated behind the microbubble generator 23. Therefore, the convex microbubble generating part 23 can also exhibit the same operational effects as the concave microbubble generating part 22 described above.

  Note that the convex shape of the microbubble generator 23 has a triangular cross-sectional shape as viewed in the axial direction of the rotor core 20 as shown in FIGS. 5 and 6 as long as it can generate negative pressure as in the concave shape. Besides, other cross-sectional shapes such as a quadrangle, a polygon, and a semicircle may be used. Further, since the negative pressure increases as the outer peripheral shape of the rotor changes abruptly with respect to the oil flow direction, the convex shape of the microbubble generator 23 is the rotor 10 (rotor core 20) as shown in FIGS. It is preferable that the rear end 23a is returned to the outer diameter of the rotor 10 in a substantially perpendicular direction with respect to the rotational direction. Further, the number of convex portions of the microbubble generator 23 may be singular or plural.

  In addition to the plurality of convex shapes along the rotation direction of the rotor 10, the microbubble generating portion 23 has a shape that intersects the oil flow direction (rotor rotation direction) (for example, a spiral shape) on the outer periphery of the rotor. It is good also as a linear member provided in the surface.

  It is also possible to combine the concave shape of the microbubble generator 22 and the convex shape of the microbubble generator 23 and provide both on the outer periphery of the rotor 10.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment described above in that it includes a microbubble generator 90 that mixes microbubbles B into the cooling oil A before the oil A is introduced into the shaft 58. .

  The microbubble generator 90 uses a swirling flow method, a pressure dissolution method, a fine hole method, or the like to dissolve air by introducing air into the oil A introduced into the shaft 58 from an oil supply source (not shown). The microbubble B is mixed.

  When the oil mixed with the microbubbles B is introduced into the rotating electrical machine 100 by the microbubble generator 90, the oil A mixed with the microbubbles B becomes the outer periphery of the rotor 10 (the rotor 10 and the stator 50). In addition, air dissolved in the oil A and deposited in the oil A is precipitated as microbubbles B by the microbubble generators 22 and 23, so that more microbubbles B between the rotor 10 and the stator 50. And a thicker air film can be formed on the rotor surface (the outer peripheral surface 20a of the rotor core 20). As a result, the drag torque between the rotor 10 and the stator 50 can be further reduced. .

  Further, air is dissolved in the introduced oil A to the vicinity of the solubility by the microbubble generator 90. For this reason, the microbubbles B can be deposited even with a small negative pressure (at the time of low rotation), and the drag torque between the rotor 10 and the stator 50 can be further reduced.

  In addition, since the microbubbles B are mixed into the oil A by the microbubble generator 90, the apparent density of the oil A is reduced according to the mixing ratio of the microbubbles B. When the density of the oil A is reduced, the oil agitation resistance on the side surface of the end plate 29 is reduced, so that the oil agitation loss is reduced. Further, when the density of the oil A is reduced, the flow rate of the oil A is increased. Here, since the heat transfer rate is proportional to the flow rate, the heat transfer rate is improved if the flow rate of the oil A is increased. Thereby, the heat absorption by the oil A passing through the refrigerant passage 43 of the rotor 10 is promoted, so that the cooling performance of the rotor 10 is improved.

  As mentioned above, although preferred embodiment was shown and demonstrated about this invention, this invention is not limited by these embodiment. For example, in the above-described embodiment, the oil A is exemplified as the refrigerant for cooling the rotating electrical machine 100, but another one having a cooling effect may be used. Further, the configuration of the refrigerant passage 43 formed in the end plate 29 of the rotor 10 and the installation position of the discharge hole 44 communicating with the refrigerant passage 43 may be different from the configuration and position illustrated in the above embodiment. .

  DESCRIPTION OF SYMBOLS 10 ... Rotor, 22, 23 ... Micro bubble generation part, 50 ... Stator, 58 ... Shaft, 90 ... Micro bubble generator, 100 ... Rotating electric machine, A ... Cooling oil (refrigerant), B ... Micro bubble.

Claims (4)

The refrigerant introduced into the rotatable shaft is supplied to the stator side disposed on the outer periphery of the rotor by a centrifugal force generated by the rotation of the rotor fixed around the shaft. In the cooling device for cooling
A cooling device for a rotating electrical machine, comprising a microbubble generator provided on an outer periphery of the rotor and generating microbubbles by rotation of the rotor.   2. The cooling device for a rotating electrical machine according to claim 1, wherein the microbubble generating portion is a concave-shaped portion formed on an outer periphery of the rotor.   The cooling device for a rotating electric machine according to claim 1, wherein the microbubble generating part is a convex part formed on an outer periphery of the rotor.   The cooling device for a rotating electrical machine according to any one of claims 1 to 3, further comprising a microbubble generator that mixes microbubbles into the refrigerant introduced into the shaft.

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