JP7650449B2 - Cooling structure for rotating electrical machines - Google Patents

Description

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

Conventionally, rotating electric machines have been known that are equipped with a cooling structure that brings cooling oil into contact with the coil end portions of the stator to improve the cooling efficiency of the coils wound around the stator core.

In this type of rotating electric machine, the vertically upper region of the coil end is supplied with cooling oil, whereas the vertically lower region comes into contact with the heated cooling oil, which does not promote heat exchange and is prone to temperature unevenness in the coil end. For this reason, a cooling structure has been proposed in which ridges are formed on the wall surface of the cover part facing the coil end, and the ridges guide the cooling oil collected on the wall surface side and drip it down to the underside of the coil end (see, for example, Patent Document 1).

JP 2012-65384 A

In the cooling structure of Patent Document 1, the temperature of the cooling oil guided to the underside of the coil end portion via the ridges of the cover portion is equal to or higher than the temperature of the cooling oil discharged from the coolant supply portion. In addition, the cooling oil guided to the ridges of the cover portion and flowing to the underside is only a portion of the cooling oil sprayed from the upper side of the coil end portion. Therefore, the cooling effect of the cooling structure of Patent Document 1 on the underside of the coil end portion is limited, and there is still room for improvement in suppressing temperature unevenness between the upper and lower sides of the coil end portion.

The present invention was made in consideration of the above situation, and provides a cooling structure for a rotating electric machine that can efficiently cool the vertically lower area of the coil end portion and suppress temperature unevenness in the coil end portion.

One aspect of the present invention is a cooling structure for a rotating electric machine, the cooling structure including a housing cover attached to a housing that accommodates the rotating electric machine and disposed opposite a coil end portion of the rotating electric machine. The housing cover has an inner wall portion having a bearing portion that receives a rotating shaft of the rotating electric machine and is spaced axially from the coil end portion, the inner wall portion having a bearing portion that receives a rotating shaft of the rotating electric machine and that guides cooling oil supplied from a vertically upper side of the rotating electric machine to a lower side along a plane that intersects with the rotating shaft, an oil guide attached to the inner wall portion vertically lower than the bearing portion and that guides the cooling oil guided by the inner wall portion to an inner periphery vertically below the coil end portion, and a cooling portion having a refrigerant piping that is thermally connected to the inner wall portion and that cools the cooling oil guided to the inner wall portion.

The cooling portion may be disposed in a region of the inner wall portion vertically above the bearing portion.

The cooling structure for a rotating electric machine according to one aspect of the present invention can efficiently cool the vertically lower region of the coil end portion, thereby suppressing temperature unevenness in the coil end portion.

1 is a vertical cross-sectional view showing an example of a rotating electric machine according to an embodiment of the present invention; 2 is a perspective view of an example of a housing cover portion of the embodiment. FIG. FIG. 6A and 6B are diagrams illustrating the flow of a refrigerant inside the housing cover portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, in the drawings, the same elements are given the same reference numerals. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown only for illustrative purposes, and do not represent the actual shapes, dimensions, etc.

Figure 1 is a vertical cross-sectional view showing an example of a rotating electric machine of this embodiment. The rotating electric machine 1 of this embodiment is an inner rotor type motor, and includes a rotor 2 and a stator 3. Figure 1 partially shows the non-load side of the rotating electric machine 1.

The rotor 2 is, for example, a magnet-embedded type or a surface magnet type rotor. A shaft 4 is fitted into the center of the rotor 2 so as to penetrate the iron core along the rotation axis AX. In the following description, the circumferential direction centered on the rotation axis AX is simply referred to as the circumferential direction, and the radial direction centered on the rotation axis AX is simply referred to as the radial direction.

The stator 3 has a cylindrical stator core and is arranged concentrically on the outer periphery of the rotor 2 with a small air gap between them. A number of slots (not shown) are formed along the axial direction on the inner periphery of the stator 3, and coils are wound in the slots. The coil end portions 5 of the coils protrude from the stator 3 at both axial ends of the stator 3, forming an annular shape in the circumferential direction.

In the rotating electric machine 1, the magnetic field of the stator 3 is switched in sequence by controlling the current through the coil, which generates an attractive or repulsive force with the magnetic field of the rotor 2. This causes the rotor 2 and the shaft 4 to rotate, driving the rotating electric machine 1. At this time, the coil generates heat due to the current passing through it.

The rotating electric machine 1 of this embodiment is housed in a rotating electric machine housing having a housing body 6 and a housing cover portion 7. Both the housing body 6 and the housing cover portion 7 are manufactured by casting.

The housing body 6 of the rotating electrical machine housing is a case having a cylindrical space that is open on one side and the other side in the axial direction. The rotor 2 and the stator 3 are arranged in the cylindrical space of the housing body 6. For example, the stator 3 is fitted to the inner circumference of the housing body 6, and the housing body 6 is attached so as to cover the outer circumference of the stator 3.

A housing cover portion 7 is attached to one side and the other side of the housing body 6, spaced apart from the coil end portion 5 in the axial direction, and the openings on both sides of the housing body 6 are closed by the housing cover portion 7. The shaft 4 is rotatably supported by a bearing 7b provided in a bearing portion 7a of the housing cover portion 7. Note that FIG. 1 shows only the configuration of the housing cover portion 7 on the anti-load side, and the housing cover portion on the load side is omitted.

As shown in FIG. 1, a circuit housing 8 is attached to a housing cover part 7 on the anti-load side (one side) of the rotating electric machine housing. The circuit housing 8 houses a control board 9 of an inverter circuit that converts DC voltage from an external power source (not shown) into AC and supplies it to the coil.

The rotating electrical machine housing also has a discharge oil passage 11 for oil cooling the coil end portion 5. The discharge oil passage 11 is an oil passage through which oil cooled by an oil cooler (not shown) flows. The discharge oil passage 11 is disposed above the stator 3 in Figures 1 and 2, and extends in the axial direction within the housing main body 6 and the housing cover portion 7. A first inlet hole 12 and a second inlet hole 13 branching off from the discharge oil passage 11 are formed in the housing cover portion 7.

The first inlet hole 12 is formed to extend radially downward from the end of the discharge oil passage 11 and communicates with the inside of the housing cover portion 7 at a position facing the outer circumferential surface of the coil end portion 5. The first inlet hole 12 serves to disperse oil from the discharge oil passage 11 to the coil end portion 5 from above.

The second inlet hole 13 is formed at an angle downward in the axial direction from the end of the discharge oil passage 11 and communicates with the inside of the housing cover part 7 at a position facing the inner wall surface 14 of the housing cover part 7. The second inlet hole serves to guide oil from the discharge oil passage 11 toward the inner wall surface 14 of the housing cover part 7 that faces the coil end portion 5.

As shown in FIG. 2, an oil guide 15 is attached to the inner wall surface 14 of the housing cover portion 7 to guide the oil flowing along the inner wall surface 14 to the lower region of the coil end portion 5. The oil guide 15 is a flat plate-shaped member bent in a V-shape so as to form a downward convexity toward the center, and is attached below the bearing portion 7a. The oil guide 15 is positioned within the housing cover portion 7 so that one long side is in contact with the inner wall surface 14 and the other long side faces the coil end portion 5.

Figure 3 is a plan view of the oil guide 15. A first auxiliary guide portion 15a and a second auxiliary guide portion 15b are provided on the upper surface of the other long side of the oil guide 15. The first auxiliary guide portion 15a is formed in the center of the oil guide 15. The second auxiliary guide portions 15b are formed on both sides of the oil guide 15 in the longitudinal direction, separated by the first auxiliary guide portion 15a in the center.

The first auxiliary guide portion 15a is a protrusion that is arranged to extend in an oblique direction relative to the longitudinal direction of the oil guide 15 so that one side of the oil guide 15 is closer to the center than the other side. The first auxiliary guide portion 15a guides the oil flowing on the upper surface of the oil guide 15 so that it drips onto the coil end portion 5 near the central portion of the oil guide. The second auxiliary guide portion 15b is a protrusion that extends in the longitudinal direction of the oil guide 15 along the edge of the other side of the oil guide 15. The second auxiliary guide portion 15b prevents oil from spilling to the other side at locations other than the central portion of the oil guide 15.

The area near the bottom of the rotating electrical housing functions as an oil pan in which oil that has been heat exchanged with the coil end portion 5 is stored, and the housing body 6 is provided with a suction outlet (not shown) for sucking out the oil stored in the oil pan. The suction outlet of the housing body 6 is connected to a flow path that communicates with an oil pump (not shown).

Next, the configuration of the housing cover portion 7 of the rotating electrical machine housing will be described.
The housing cover part 7 is configured in a box shape. A first cooling part 21, a second cooling part 22, and a resolver 23 are accommodated in the internal space of the housing cover part 7 formed between the inner wall surface 14 and the circuit housing 8. The resolver 23 is a detector that detects the rotation angle of the shaft 4, and is attached to the anti-load side of the shaft 4.

The first cooling unit 21 is disposed in a region vertically above the bearing portion 7a of the housing cover portion 7, and is a device for cooling the oil flowing on the inner wall surface 14 of the housing cover portion 7. As shown in FIG. 4, the first cooling unit 21 has a refrigerant pipe 21a thermally connected to the inner wall surface 14 of the housing cover portion 7. The refrigerant pipe 21a of the first cooling unit 21 is connected to a refrigerant inlet 24 that receives refrigerant supplied from the outside of the housing cover portion 7. The refrigerant pipe 21a is disposed in a serpentine manner so that the pipe extends in a horizontal direction perpendicular to the vertical direction within a plane along the inner wall surface 14 of the housing cover portion 7. The second cooling unit 22 is connected to the downstream side of the refrigerant pipe 21a of the first cooling unit 21. As a result, the refrigerant flowing through the refrigerant pipe 21a exchanges heat with the oil flowing along the inner wall surface 14 of the housing cover portion 7, thereby cooling the oil.

The second cooling unit 22 is disposed on the circuit housing 8 side of the housing cover part 7, and is a device for cooling the control board 9 disposed within the circuit housing 8. The second cooling unit 22 is thermally connected to the wall surface on the circuit housing 8 side of the housing cover part 7, and cools the control board 9 by flowing the refrigerant received from the first cooling unit 21. The downstream side of the second cooling unit 22 is connected to a refrigerant outlet 25 that discharges the refrigerant to the outside of the housing cover part 7.

The flow of oil in the rotating electrical machine 1 of this embodiment will be described below.
Oil stored in an oil pan of the housing of the rotating electrical machine is sucked out from a suction port (not shown) by driving an oil pump, cooled in an oil cooler (not shown), and then sent to a discharge oil passage 11 located on the upper side of the housing of the rotating electrical machine. In the discharge oil passage 11, the oil flows to one side (anti-load side) and the other side (load side) in the axial direction, but the following description will focus on the oil flowing toward one side of the discharge oil passage 11.

The oil flowing on one side of the discharge oil passage 11 branches into a first inlet hole 12 and a second inlet hole 13 at the end of the discharge oil passage 11. The oil that flows into the first inlet hole 12 is sprayed onto the coil end portion 5 from above, and flows downward around the outer periphery of the coil end portion 5 from both the left and right directions. As a result, the oil that comes into contact with the coil end portion 5 absorbs heat, cooling the coil end portion 5. Here, the temperature of the oil sprayed onto the coil end portion 5 from above increases as it flows downward due to heat exchange. Therefore, the oil sprayed onto the coil end portion 5 from above cools the upper region of the coil end portion 5 more effectively than the lower region.

Meanwhile, the oil that flows into the second inlet hole 13 is guided to the inner wall surface 14 of the housing cover part 7 and flows downward along the inner wall surface 14 of the housing cover part 7. Since the first cooling part 21 is arranged above the bearing part 7a on the inner wall surface 14 of the housing cover part 7, the oil that flows along the inner wall surface 14 of the housing cover part 7 is cooled by heat exchange with the first cooling part 21. The cooled oil then reaches the oil guide 15, and the oil guided to the center of the oil guide 15 drips to the other side. As a result, the oil that drips from the oil guide 15 comes into contact with the inner circumference of the coil end part 5 in the area below the coil end part 5 and removes heat.

Oil that has passed through the inner wall surface 14 of the housing cover portion 7 and has been cooled by the first cooling portion 21 is dripped directly onto the lower region of the coil end portion 5 by the oil guide 15 without coming into contact with the upper region of the coil end portion 5. This improves the cooling efficiency of the lower region of the coil end portion 5, thereby suppressing temperature unevenness between the upper and lower regions of the coil end portion 5.

In addition, the oil running along the inner wall surface 14 of the housing cover portion 7 is cooled by the first cooling portion 21, and therefore its temperature is lower than that of oil not cooled by the first cooling portion 21 (oil sprayed from above). Therefore, according to this embodiment, even if the flow rate of oil running along the inner wall surface 14 of the housing cover portion 7 is small, the area below the coil end portion 5 can be efficiently cooled.

In addition, the oil sprayed from above onto the coil end portion 5 and the oil dripped onto the inner circumference of the coil end portion 5 by the oil guide 15 both join together and are stored in the oil pan, and are then sent out again towards the oil cooler by driving the oil pump. In this embodiment, because part of the oil is also cooled by the first cooling section 21, the temperature of the oil stored in the oil pan is lower than when the first cooling section 21 is not present. Therefore, in this embodiment, the load on the oil cooler that cools the oil from the oil pan is also reduced, and costs can be reduced by reducing the capacity of the oil cooler.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

In the above embodiment, a motor configuration example was described as an example of a rotating electric machine, but the rotating electric machine of the present invention can also be applied to an oil-cooled generator.

In addition, in the above embodiment, an example of the configuration of the housing cover part on the anti-load side was described, but the housing cover part on the load side is also configured in the same manner as the anti-load side. Note that the housing cover part on the load side differs from the housing cover part on the anti-load side in that it does not have a second cooling part.

In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1... rotating electric machine, 2... rotor, 3... stator, 4... shaft, 5... coil end portion, 6... housing main body, 7... housing cover portion, 7a... bearing portion, 7b... bearing, 11... discharge oil passage, 12... first inlet hole, 13... second inlet hole, 14... inner wall surface, 15... oil guide, 21... first cooling portion, 22... second cooling portion

Claims (2)

A cooling structure for a rotating electric machine, comprising: a housing cover attached to a housing that accommodates a rotating electric machine and disposed opposite a coil end portion of the rotating electric machine,
The housing cover includes:
an inner wall portion having a bearing portion for receiving a rotating shaft of the rotating electric machine and spaced apart in the axial direction from the coil end portion, the inner wall portion guiding cooling oil supplied from an upper side of the rotating electric machine in a vertical direction to a lower side along a plane intersecting the rotating shaft;
an oil guide attached to the inner wall portion vertically below the bearing portion and configured to guide the cooling oil guided by the inner wall portion to an inner periphery vertically below the coil end portion;
a cooling unit including a refrigerant pipe that is arranged in a serpentine manner so as to extend horizontally within a plane along the inner wall portion and is thermally connected to the inner wall portion, and that cools the cooling oil that is guided to the inner wall portion;
A cooling structure for a rotating electric machine having the above structure. The cooling structure for a rotating electric machine according to claim 1 , wherein the cooling portion is disposed in a region of the inner wall portion vertically above the bearing portion.

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