WO2007094350A1

WO2007094350A1 - Cooling structure of dynamo-electric machine

Info

Publication number: WO2007094350A1
Application number: PCT/JP2007/052596
Authority: WO
Inventors: Tetsuro Ogushi; Seiji Haga; Nobuhiro Kanei
Original assignee: Mitsubishi Electric Corporation
Priority date: 2006-02-16
Filing date: 2007-02-14
Publication date: 2007-08-23
Also published as: JP4786702B2; JPWO2007094350A1

Abstract

In order to provide the cooling structure of a dynamo-electric machine in which cooling efficiency of a rotor is enhanced, linear protrusions protruding radially inward and extending in the axial direction are provided tightly on the inner circumferential surface of the coolant passage of a rotor shaft. The protrusions are a plurality of rod members supported at the opposite ends tehreof by two ring members press fitted to the inner circumferential surface of the coolant passage. The protrusion has a height equal to 10-15% of the inside diameter of the coolant passage. In the coolant passage, a disc having an orifice of inside diameter dimension equal to 20-40% of the inside diameter of the coolant passage may be provided in order to generate turbulence of coolant. The orifice is arranged coaxially, eccentrically, or obliquely with respect to the coolant passage or arranged in combination of those arrangements. Protrusions not only increase the contact area between the fluid and the inner circumferential surface of the shaft but also induce turbulence of coolant flow in the shaft, whereby heat transmission from the shaft to the coolant is increased and cooling effect of the rotor is enhanced.

Description

Specification

Cooling structure of rotating electric machine

Technical field

The present invention relates to a cooling structure for a rotating electrical machine, and more particularly to a cooling structure for a rotating electrical machine such as a motor having a refrigerant passage in a rotor shaft.

Background art

Conventionally, in order to cool a rotor of a rotating electrical machine such as a motor, a cooling structure has been proposed in which a refrigerant passage is provided inside a rotor shaft to allow the refrigerant to pass therethrough. The motor includes a hollow cylindrical stator (stator) supported in a cylindrical frame, and a rotor (rotor) that is rotatably supported by the shaft and rotated in the stator. As a motor cooling structure, the shaft that supports the rotor is formed with a hollow hole in the axial direction so that cooling fluid such as air, water, ethylene glycol, and lubricating oil can pass inside. Furthermore, a projecting member inclined at a predetermined angle in the axial direction, that is, a helical fin, is inserted on the inner peripheral surface of the shaft, and the contact area between the cooling fluid and the inner peripheral surface of the shaft is increased to increase heat. In addition to improving the exchange efficiency, a flow of cooling fluid is generated in the hollow hole of the shaft when the rotor rotates. In this way, the cooling structure cools the shaft, and thus the rotor that becomes hot due to iron loss is also cooled from the inside (see, for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-34189 (page 3, lines 5 to 49, figure:! To 3)

Disclosure of the invention

Problems to be solved by the invention

[0004] However, in the motor described above, the fin has a spiral shape. Therefore, when the fluid is circulated using an external pump, the driving force of the fluid is generated in the direction opposite to the driving direction of the pump. There is a problem that the cooling capacity may decrease as a result of the flow rate decreasing. In addition, depending on the angle of the spiral fin 14, there is a problem in that the heat transfer from the shaft 11 to the fluid 13 is small because the effect of disturbing the fluid 13 is small and the cooling effect is small.

[0005] The present invention has been made to solve such problems, and its purpose is to An object of the present invention is to provide a cooling structure for a rotating electrical machine that has a high rejection efficiency and is easily manufactured. Means for solving the problem

[0006] In order to achieve the above-described object, the rotating electrical machine cooling structure of the present invention cools a rotating electrical machine including a stator, a rotor, and a shaft that rotatably supports the rotor with respect to the stator. In order to achieve this, there is provided a cooling structure for a rotating electrical machine provided with a refrigerant passage having a circular cross section provided in a shaft and extending in the axial direction through which a cooling medium can pass, and is closely attached to the inner peripheral surface of the refrigerant passage. It is provided with a linear protrusion that is provided and protrudes inward in the radial direction and extends in the axial direction. A disk having an orifice for generating a turbulent flow of the cooling medium in the refrigerant passage may be provided.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view of a rotating electrical machine to which a rotating electrical machine cooling structure of the present invention is applied. (Example 1)

FIG. 2 is a schematic cross-sectional view in a plane perpendicular to the axis of the shaft according to the present invention. (Example 1)

FIG. 3 is a schematic cross-sectional view in the axial direction of a shaft according to the present invention. (Example 1)

FIG. 4 is a schematic perspective view of an assembly having a protrusion according to the present invention. (Example 1)

FIG. 5 is a characteristic diagram showing the rate of improvement in heat transfer coefficient depending on the number of protrusions in the rotating electrical machine cooling structure of the present invention. (Example 1)

FIG. 6 is a view showing a streamline state of the cooling medium in the shaft by the cooling structure of the rotating electric machine of the present invention. (Example 1)

FIG. 7 is a schematic axial sectional view showing a shaft according to another example of a cooling structure for a rotating electrical machine of the present invention. (Example 2)

8 is a characteristic diagram showing the rate of improvement in heat transfer coefficient depending on the diameter ratio between the small-diameter pipe line and the hollow hole in the cooling structure of FIG. (Example 2)

FIG. 9 is a schematic axial sectional view showing a shaft according to still another example of the cooling structure for a rotating electrical machine of the present invention. (Example 3)

FIG. 10 is a schematic axial sectional view showing a shaft according to still another example of a cooling structure for a rotating electrical machine of the present invention. (Example 4)

BEST MODE FOR CARRYING OUT THE INVENTION [0008] Embodiment 1.

FIG. 1 shows, as an example, a motor to which the rotating electrical machine cooling structure of the present invention is applied. The present invention is applicable to general rotating electrical machines including a rotor, a generator, and the like that are driven only by a motor and equipped with a rotor that needs to be cooled.

[0009] The structure of the motor 1 itself in FIG. 1 is general, and the motor 1 is a stator (fixed) that supports a rotating part of the rotor (rotor) 2 and surrounds it in a non-contact manner. (Child) 3 and are housed in frame 4. The frame 4 has a cylindrical shape along the axial direction of the rotor 2 and the stator 3. A stator 3 is fixed at a predetermined position on the inner peripheral surface of the frame 4. The stator 3 has a thick cylindrical shape, and its outer peripheral surface has the same diameter as the inner peripheral surface of the frame 4. A coil winding 5 for forming a rotating magnetic field is wound around the stator 3, and a part of the coil winding 5 protrudes outward from both ends of the stator 3 as a coil end 6. A rotor 2 is provided inside the inner peripheral surface of the stator 3 so as not to contact the stator 3. The rotor 2 has a cylindrical shape and is provided so as to be surrounded by the stator 3 at a position corresponding to the stator 3 in the axial direction. A plurality of aluminum slot bars 7 are embedded in the port 2 along the axial direction. Since the rotor 2 and the stator 3 are provided on substantially concentric circles, the circumferential gap (gap) existing between the rotor 2 and the stator 3 is substantially constant.

Disc-shaped end brackets 8 and 9 are fixed to both ends in the longitudinal direction of the frame 4. Each of the end brackets 8 and 9 is provided with a bearing 10 at the center thereof, and a shaft 11 passes therethrough. The rotor 2 and the shaft 11 are fixed by shrinkage fitting. The shaft 11 is a hollow hole having a circular cross section, and a refrigerant passage 12 is formed coaxially in the axial direction so that a cooling medium 13 such as air, water, ethylene glycol, or lubricating oil passes through the shaft 11.

[0011] When a rotating magnetic field is formed by passing a current through the coil winding 5 wound around the stator 3, the slot bar embedded in the port 2 receives the force and the rotor 2 rotates together with the shaft 11. At the same time, an eddy current is generated in the rotor 2 due to a change in magnetic flux passing through the rotor 2. At this time, heat generated in the coil wire is conducted to the frame 4 through the stator 3 and is released from the frame 4 to the atmosphere outside the motor. In addition, when eddy current is generated in the rotor 2, the rotor 2 A force that generates heat in itself A coolant passage 12 is provided in the shaft 11 that is integrally formed by shrink fitting with the rotor 2, and is sent from a supply source. Since the incoming cooling medium 13 flows and passes, heat exchange is performed between the shaft 11 and the cooling medium 13. Therefore, the shaft 11 can be forcibly cooled, so that the rotor 2 can be cooled from the inside.

2 to 6 show details of the cooling structure for a rotating electric machine according to the present invention. On the inner peripheral surface of the refrigerant passage 12, which is a hollow through hole provided in the shaft 11 that supports the rotor 2, a protrusion 21 that protrudes radially inward from the inner peripheral surface force is provided. . The protrusion 21 extends linearly and continuously in the axial direction of the shaft 11 (that is, parallel to the axis), and is provided at a position and a length substantially corresponding to the entire length of the rotor 2.

[0013] The protrusion 21 can be provided in the refrigerant passage 12 in various manners. In the illustrated example, as shown in FIG. 4, two parallel press-fitted into the inner peripheral surface of the refrigerant passage 12 are provided. Two rod members arranged in parallel between the ring member 22 are supported by welding or the like at both ends and constitute a force-like assembly 23 as a whole. The ridge 21 is a material force having a large thermal conductivity such as copper or iron, has a uniform rectangular cross section in the axial direction, and is formed of a ridge 21 and a ring member 22. The solid 23 is shrink-fitted into the refrigerant passage 12 which is a hollow through hole having a circular cross section of the shaft 11, so that the solid 11 is in close contact with the inner peripheral surface of the refrigerant passage 12 and the heat of the shaft 11 is easily transmitted to the protrusion 21. It is like that.

Heat from the rotor 2 is conducted to the shaft 11, most of the heat is dissipated from the inner peripheral surface of the refrigerant passage 12 in the shaft 11 to the cooling medium 13, and the remaining part is cooled via the protrusion 21. Heat is radiated to the medium 13. At this time, the cooling medium 13 flowing into the refrigerant passage 12 is agitated by the protruding ridges 21 of the rotating shaft 11, and the flow is disturbed to increase the heat transfer from the shaft 11 to the cooling medium 13 and increase the cooling effect. Become.

[0015] Specifically, when the projecting member 21 has a shaft inner diameter of 40 mm, for example, a good result can be obtained by providing two projecting strips 21 having a width of 2 mm and a height of 5 mm so as to face each other in the radial direction. Figure 5 shows the results of numerical analysis of the change in heat transfer coefficient depending on the number of ridges 21 of this size. Figure 6 shows the flow velocity distribution in the shaft cross section when two ridges 21 of this size are used. As shown by the dotted line arrow in Fig. 6, the streamline changes due to the ridge 21, and it hits the inner wall surface of the shaft 11. It can be seen that there is a flow. As a result, as shown in Fig. 5, heat transfer on the inner wall surface is improved almost in proportion to the number of ridges compared to the case without ridges 21 (number of ridges = 0). .

[0016] Further, since the protrusion 21 has a uniform cross-sectional shape and dimensions in the axial direction, the cooling effect of the rotor is increased uniformly in the axial direction of the shaft. Furthermore, since the ridge 21 is composed of a member having a high thermal conductivity, the heat of the shaft 11 is also radiated to the cooling medium 13 through the ridge 21, and the heat transfer surface area is increased by the ridge 21 to increase the rotor surface. The effect of increasing the cooling effect is also obtained. If the protrusion 21 has a radial dimension (height) of 10% to 15% of the inner diameter of the refrigerant passage 12, good results can be obtained.

[0017] Embodiment 2.

FIG. 7 is an axial sectional view showing another example of the cooling structure of the rotating electric machine of the present invention. In this example, the small diameter that generates the turbulent flow of the cooling medium 13 indicated by the arrow 32 in the refrigerant passage 12 of the shaft 11 is shown. A disc 33 having an orifice 31 which is a pipe line is provided. In the example shown in the figure, the orifice 31 is a circular hole provided at the center of the disk 33 and is arranged coaxially with respect to the shaft 11, that is, with respect to the coolant passage 12. It is installed in.

The action of cooling the rotor 2 by the heat from the rotor 2 being radiated to the fluid 13 in the shaft 11 is the same as in the previous example. At this time, since the sectional area of the orifice 31 is small, the flow velocity increases, and the fluid 13 flows out into the shaft 11 as shown by the solid arrow 32 in the figure, and synergizes with the effect of the rotation of the shaft. As a result, a flow effect on the inner wall is induced. As a result, the heat transfer coefficient inside the shaft 11 is improved and the cooling effect of the rotor is increased.

[0019] Fig. 6 shows the promotion rate of the heat transfer coefficient with respect to the diameter ratio of the orifice (small-diameter pipe) 31 and the refrigerant passage 12 at this time (= increase rate of the heat transfer coefficient when there is no hollow hole). Shown in. The figure shows that the diameter ratio between the small-diameter pipe 31 and the refrigerant passage 12 is 0.4 or less, and the acceleration rate is 5% or more. . Good results can be obtained when the inner diameter of the orifice 31 is 20% to 40% of the inner diameter of the refrigerant passage 12. The inner diameter of the orifice 31 is 20. If it is smaller than / o, the flow rate of the cooling medium 13 is insufficient. Sufficient cooling is difficult, and if it exceeds 40%, the flow rate of the cooling medium 13 through the orifice 31 does not become sufficiently high.

[0020] Embodiment 3.

FIG. 9 is an axial cross-sectional view showing still another example of the cooling structure for a rotating electrical machine of the present invention. At the inlet of the cooling medium 13 to the shaft 11 having the refrigerant passage 12, an orifice 41 that is a small-diameter pipe is provided away from the central axial force of the shaft 11. In this example, the orifice 41 is a small-diameter hole provided eccentrically on the disc 43 and extending in the axial direction of the shaft 11. The heat from the port 2 is radiated to the cooling medium 13 through the shaft 11 and the rotor 2 is cooled. At this time, the flow of the cooling medium 13 is accelerated by the orifice 41 having a small cross-sectional area, and is eccentric with respect to the refrigerant passage 12, so that the cooling medium 13 has an effect of rotation of the shaft 11 as shown by a solid line arrow 42 in the figure. Synergistically, it turns into a jet swirl and flows into the shaft 11. For this reason, a flow that strikes the inner wall of the shaft 11 is induced. As a result, the heat transfer rate inside the shaft 11 is improved, and the cooling effect of the rotor 2 is increased. Other configurations may be the same as the example shown in FIG.

[0021] Embodiment 4.

FIG. 10 is an axial cross-sectional view showing still another example of the cooling structure for a rotating electrical machine of the present invention. A disc 53 is provided at the inlet of the refrigerant passage 12, and an orifice 51, which is a small-diameter pipe whose axis is inclined with respect to the central axis direction of the shaft 11, is provided at the center of the disc 53. It is provided. Also in this example, the cooling medium 13 has a small flow passage cross-sectional area at the orifice 51, so that the flow velocity increases, and as shown by the solid line arrow 52 in the figure, the cooling medium 13 is jetted together with the effect of the rotation of the shaft 11. As a swirling flow, it flows out into the shaft 11 and a flow is induced against the inner wall of the shaft 11, resulting in an improvement in the heat transfer coefficient inside the shaft 11 and an increase in the cooling effect of the rotor. . Other configurations may be the same as the example shown in FIG.

[0022] In the above example, the cooling structure of the rotating electrical machine of the present invention has been described as being separate from each other. However, these may be used in an appropriate combination within a range where there is no inconvenience, and the flow of the cooling medium 13 is further stirred. It can also be promoted. For example, the linear protrusion 21 shown in FIGS. 1 to 6 can be combined with the orifice 31 shown in FIG. 7, and the eccentric orifice 41 shown in FIG. 9 can be inclined like the orifice 51 shown in FIG.

Claims

The scope of the claims

[1] In order to cool a rotating electrical machine including a stator, a rotor, and a shaft that rotatably supports the rotor with respect to the stator, a cooling medium can be provided on the shaft and can pass a cooling medium. A cooling structure for a rotating electrical machine including a refrigerant passage having a circular cross section extending in an axial direction,

A cooling structure for a rotating electrical machine, comprising a linear protrusion provided in close contact with the inner peripheral surface of the refrigerant passage, protruding inward in the radial direction and extending in the axial direction.

2. The cooling structure for a rotating electric machine according to claim 1, wherein the protrusion has a radial dimension of 10% to 15% of the inner diameter of the refrigerant passage.

[3] The rotating electric machine according to claim 1 or 2, wherein the protrusions are a plurality of rod members supported at both ends by two ring members press-fitted into the inner peripheral surface of the refrigerant passage. Cooling structure.

[4] In order to cool a rotating electrical machine including a stator, a rotor, and a shaft that rotatably supports the rotor with respect to the stator, a cooling medium can be provided on the shaft and can pass a cooling medium. A cooling structure for a rotating electrical machine including a refrigerant passage having a circular cross section extending in an axial direction,

A cooling structure for a rotating electrical machine, comprising a disk provided in the refrigerant passage and having an orifice for generating a turbulent flow of the cooling medium in the refrigerant passage.

5. The cooling structure for a rotating electric machine according to claim 4, wherein the orifice has an inner diameter dimension of 20% to 40% of an inner diameter of the refrigerant passage.

6. The cooling structure for a rotating electric machine according to claim 4 or 5, wherein the orifice is coaxial with the refrigerant passage.

7. The cooling structure for a rotating electric machine according to claim 4 or 5, wherein the orifice is eccentric with respect to the refrigerant passage.

8. The cooling structure for a rotating electric machine according to claim 4 or 5, wherein the orifice is inclined with respect to the refrigerant passage.