Rotary electric machine

Abstract

To provide a rotary electric machine that can reduce a temperature rise of a bearing and extend the lubrication life of the bearing.SOLUTION: A rotary electric machine 1 comprises: a rotator 6 that is disposed between a first bracket 5a and a first bearing 4a and between a second bracket 5b and a second bearing 4b, which are each arranged at a predetermined distance from each other in an axis direction, and that rotates with a shaft 8; and a stator 2 that is disposed at a predetermined air gap in a radial direction from the rotator. The rotary electric machine comprises a plurality of internal air paths 2b into which cooling air is taken from a first end side of the stator adjacent to the first bearing and out of which cooling air is exhausted from a second end side of the stator adjacent to the second bearing. Each internal air path is formed of: a first flow path in which cooling air flows around an outer periphery of the stator, between the stator and the rotator, and on the inside of the rotator; and a second flow path in which separate cooling air which does not flow in the first flow path flows. The second bearing is arranged adjacent to a flow path through which the separate cooling air that has flown in the second flow path passes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotating electric machine, and more particularly to a rotating electric machine having an improved cooling structure for a bearing. [Background technology]

[0002] Generally, as the power density of a rotating electrical machine increases, the coil temperature increases, which in turn increases the temperature of the cooling air in the rotating electrical machine and the temperature of the bearings.

[0003] The bearings of rotating electrical machines are lubricated with grease or oil, and reducing the temperature rise in the bearings reduces the deterioration of the grease or oil, leading to an extension of the lubrication life of the bearings.

[0004] As a prior art document relating to a cooling structure in a bearing portion of such a rotating electric machine, Patent Document 1 entitled "Totally Enclosed Rotating Electric Motor" can be mentioned.

[0005] Patent Document 1 describes a "totally enclosed rotary motor" that can efficiently cool the interior of the machine and reduce noise, and that includes a stator core, a sealed case having first and second brackets fixed to both axial ends of the stator core, a first bearing attached to the first bracket at one end of the stator core, a second bearing attached to the second bracket at the other end of the stator core, a shaft rotatably supported by the first and second bearings and extending inside the case, a rotor core attached to the shaft and provided on the inner side of the stator core, a ventilation fan attached to the shaft between the first bearing and the rotor core and rotatable integrally with the shaft, an air intake formed in the first bracket near the first bearing, and an outside air flow passage that guides outside air drawn in from the air intake from the first bearing side to the second bearing side by the rotation of the ventilation fan. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-98791 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the structure of the "totally enclosed rotary motor" described in Patent Document 1 mentioned above, it is necessary to ensure the length required to fix the ventilation fan to the shaft, and since the cooling performance depends on the rotation, at low rotation speeds there is a possibility that cooling will be poor and the bearings will heat up, which may shorten the lubrication life of the bearings.

[0008] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a rotating electric machine capable of reducing the temperature rise of the bearings and extending the lubrication life of the bearings. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the rotating electric machine of the present invention is provided with: a first bracket and a second bracket fixed to a stator frame; a first bearing and a second bearing held by the first bracket and the second bracket; a rotor arranged between the first bracket and the first bearing and the second bracket and the second bearing arranged at a predetermined distance in the axial direction and rotating together with the shaft; and a stator arranged with a predetermined air gap in the radial direction from the rotor, the rotating electric machine having a plurality of internal air flow passages through which cooling air is taken in from a first end side of the stator adjacent to the first bearing and the cooling air is discharged from a second end side of the stator adjacent to the second bearing, the plurality of internal air flow passages comprising a first flow passage through which the cooling air flows around the outer periphery of the stator, between the stator and the rotor, and inside the rotor, and a second flow passage provided in the stator frame through which another cooling air flows that does not flow through the first flow passage, and the second bearing is arranged adjacent to the flow passage through which the other cooling air that has flowed through the second flow passage passes. Effect of the Invention

[0010] According to the present invention, it is possible to reduce the temperature rise of the bearing and extend the lubrication life of the bearing. [Brief description of the drawings]

[0011] [Figure 1] 1 is a vertical sectional view showing a first embodiment of a rotating electric machine according to the present invention; [Diagram 2] 2 is an enlarged cross-sectional view showing the periphery of a bearing portion on the exhaust side of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The rotating electrical machine of the present invention will be described below based on the illustrated embodiments. In the drawings, the same reference numerals are used for the same components. EXAMPLES

[0013] FIG. 1 shows a rotating electric machine 1 according to a first embodiment of the present invention.

[0014] The rotating electric machine 1 of this embodiment shown in Figure 1 is roughly composed of a stator 2, a stator frame 3 that supports the stator 2, a first bracket 5a and a second bracket 5b that are fixed to the stator frame 3 and hold a first bearing 4a and a second bearing 4b, a rotor 6 that rotates while being held by the first bearing 4a and the second bearing 4b, a rotor core 7 and a shaft 8 that constitute the rotor 6, and a fan 9 that is attached to the shaft 8 and introduces cooling air into the rotating electric machine 1.

[0015] In addition, a fan 9 attached to the stator frame 3 introduces outside air (cooling air) 10 from the air inlet 3a of the stator frame 3 to cool the stator 2 and the rotor 6, and then expels the inside air 16 that has finished cooling the stator 2 and the rotor 6 to the outside from the exhaust port 11 of the stator frame 3.

[0016] Next, a typical cooling system for a rotating electrical machine will be described.

[0017] First, the outside air (cooling air) 10 taken in from the fan 9 is introduced into the rotating electric machine 1 from the first end side (right side in FIG. 1) of the stator 2 adjacent to the first bearing 4a, and passes through the ventilation passage (inner air flow passage) 7a of the rotor core 7 toward the inside of the rotor 6. The inner air 16 that passes through the ventilation passage 7a is divided into a first inner air 12a that flows into the stator coil end portion 2a, a second inner air 12b that flows through the air gap (inner air flow passage) G formed between the stator 2 and the rotor 6, and a third inner air 12c that flows through the inner air flow passage 2b formed on the outer periphery of the stator 2 (the flow passage (ventilation passage 7a, air gap G, and inner air flow passage 2b) through which the first inner air 12a, the second inner air 12b, and the third inner air 12c pass is the first flow passage), and the stator 2 and the rotor 6 in the rotating electric machine 1 are cooled by these inner airs (cooling air).

[0018] In addition, the first internal air 12a flowing into the stator coil end portion 2a cools the stator coil end portion 2a, then merges with the second internal air 12b and the third internal air 12c, and finally, on the side where the second bracket 5b on the exhaust side is located, i.e., the first internal air 12a cools and raises the temperature of the stator coil end portion 2a downstream of the cooling air, then merges with the second internal air 12b and the third internal air 12c, and is discharged from the exhaust port 11 of the stator frame 3 on the second end side of the stator 2 adjacent to the second bearing 4b, as shown by arrow 13.

[0019] The above is the configuration of a typical rotating electric machine, in particular the cooling system of the rotating electric machine 1, in which outside air (cooling air) 10 is introduced into the interior of the rotating electric machine 1 and inside air 16 is caused to flow in one direction parallel to the shaft 8 of the rotor 6 to cool the rotor 6 and the stator 2.

[0020] In this cooling system, the first internal air 12a, the second internal air 12b, and the third internal air 12c, which cool the rotor 6 and the stator 2 and have increased temperatures, may increase the temperature of the second bearing 4b.

[0021] For this reason, in this embodiment, in order to prevent overheating of the second bearing 4b, a bearing side flow passage 14a through which unheated cooling air 15 flows is provided on the side of the second bracket 5b to which the second bearing 4b is attached, downstream of the cooling air.

[0022] Furthermore, cooling air 15 separate from the first internal air 12a, the second internal air 12b, and the third internal air 12c is introduced from the ventilation passage 21, which is a second flow path provided in the stator frame 3 (the first internal air 12a, the second internal air 12b, and the third internal air 12c do not flow through this second flow path), to the bearing side flow path 14a, and the second bearing 4b is cooled by flowing this cooling air 15 through the bearing side flow path 14a.

[0023] FIG. 2 shows an enlarged view of the exhaust side bearing portion and its surroundings in FIG.

[0024] As shown in FIG. 2, heat flows into the second bearing 4b by heat transfer from the internal air 16, which is the merging of the first internal air 12a, the second internal air 12b, and the third internal air 12c, to the second bracket 5b, and then by heat conduction from the second bracket 5b to the second bearing 4b.

[0025] Specifically, heat is transferred from the second bracket 5b to the outer ring 4c, grease 4g, and rolling elements 4d that constitute the second bearing 4b. Some heat is transferred from the stator 2 to the second bracket 5b via thermal conduction through the stator frame 3. Some heat is transferred from the shaft 8 to the inner ring 4f, rolling elements 4d, and grease 4g that constitute the second bearing 4b. There is also heat generated by friction between the rolling elements 4d and the inner ring 4f and outer ring 4c, and by the rolling elements 4d stirring the grease 4g.

[0026] Usually, when there is no device for cooling the lubricant of the second bearing 4b, the cooling of the second bearing 4b is mainly performed by heat transfer from the bearing box 17 exposed to the outside air to the outside air. In particular, in a grease-lubricated rolling bearing, there are basically no other cooling elements.

[0027] For this reason, in this embodiment, in order to reduce the temperature of the second bearing 4b, suppress the deterioration of the grease 4g, and extend the lubrication life of the second bearing 4b, a simple structure is realized that reduces the heat input to the second bearing 4b and improves cooling. That is, in order to reduce the heat input to the second bracket 5b from the inside air 16 where the first inside air 12a, the second inside air 12b, and the third inside air 12c join, a bearing side flow passage 14a is provided at a portion exposed to the inside air 16 on the inside air 16 side of the second bracket 5b, and cooling air 15 is introduced from the ventilation passage 21 into this bearing side flow passage 14a.

[0028] Specifically, a partition plate 18 fixed to the second bracket 5b with bolts 22 is arranged on the inside air 16 side of the second bracket 5b, separating the bearing side flow path 14a from the anti-bearing side flow path 14b through which the inside air 16 where the first inside air 12a, the second inside air 12b and the third inside air 12c join passes.

[0029] Furthermore, when the partition plate 18 is fixed to the second bracket 5b with the bolts 22, a sponge-like gasket 19 is interposed between the fixed portion of the partition plate 18, thereby sealing the bearing side flow path 14a and the anti-bearing side flow path 14b and preventing the inside air 16 from passing between the bearing side flow path 14a and the anti-bearing side flow path 14b.

[0030] In other words, the originally formed ventilation passage on the exhaust side of the rotating motor 1 is separated into two by a partition plate 18, with the inside air 16 passing through one ventilation passage (the anti-bearing side flow passage 14b) and cooling air different from the inside air 16 (cooling air 15 from the ventilation passage 21) passing through the other ventilation passage (the bearing side flow passage 14a).

[0031] At this time, a pipe 20 and a valve (not shown) for connecting the bearing side flow passage 14a to the outside air may be provided to guide low-temperature outside air to the bearing side flow passage 14a.

[0032] The partition plate 18 provided on the second bracket 5b described above also acts as a thermal resistance against the heat transmitted from the stator 2 through the stator frame 3, thereby suppressing the heat input to the second bearing 4b and reducing the temperature rise of the second bearing 4b.

[0033] Furthermore, in this embodiment, a ventilation passage 21 is provided in the stator frame 3 in addition to the flow paths of the first internal air 12a, the second internal air 12b, and the third internal air 12c. Therefore, by introducing cooling air 15 from the ventilation passage 21 into the axial flow side flow path 14a separated by the partition plate 18, it is possible to remove heat from the outer surface on the inside side of the second bracket 5b.

[0034] The ventilation passage 21 provided in the stator frame 3 is a passage through which the cooling air 15 passes without passing through the stator 2 and the rotor 6, and therefore can suppress heat input from the stator 2 and the rotor 6 and introduce the cooling air 15, which has a lower temperature than the first internal air 12a, the second internal air 12b, and the third internal air 12c, into the bearing side passage 14a. This cooling air 15 cools the outer surface of the second bracket 5b on the machine inner side, and is then discharged from the exhaust port 11.

[0035] Furthermore, by providing fins on the outer surface of the second bracket 5b to improve the heat transfer characteristics of the outer surface of the second bracket 5b with the outside air, the temperature of the second bearing 4b can be reduced.

[0036] According to this embodiment, the second bearing 4b is cooled by the cooling air 15 introduced into the bearing side flow path 14a through the ventilation passage 21 provided in the stator frame 3, which is not heated by the inside air 16, so that the temperature rise of the second bearing 4b is reduced and the lubrication life of the second bearing 4b can be extended. Furthermore, a ventilation fan that rotates together with the shaft 8 to take in cooling air is not required, and the length of the shaft 8 can be shortened accordingly.

[0037] The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0038] Reference Signs List 1... rotating electric machine, 2... stator, 2a... stator coil end portion, 2b... internal air flow path, 3... stator frame, 3a... stator frame air inlet, 4a... first bearing, 4b... second bearing, 4c... outer ring, 4d... rolling element, 4f... inner ring, 4g... grease, 5a... first bracket, 5b... second bracket, 6... rotor, 7... rotor core, 7a... rotor core ventilation path, 8... Shaft, 9...fan, 10...outside air (cooling air), 11...stator frame exhaust port, 12a...first internal air, 12b...second internal air, 12c...third internal air, 14a...bearing side flow path, 14b...anti-bearing side flow path, 15...cooling air, 16...internal air, 17...bearing box, 18...partition plate, 19...gasket, 20...piping, 21...ventilation path, 22...bolt, G...air gap.

Claims

1. A rotating electric machine comprising: a first bracket and a second bracket fixed to a stator frame; a first bearing and a second bearing held by the first bracket and the second bracket; a rotor arranged between the first bracket and the first bearing and the second bracket and the second bearing arranged at a predetermined distance in the axial direction and rotating together with a shaft; and a stator arranged with a predetermined air gap in the radial direction from the rotor, a plurality of inside air flow paths through which cooling air is taken in from a first end side of the stator adjacent to the first bearing and the cooling air is discharged from a second end side of the stator adjacent to the second bearing; the plurality of inside air passages include a first passage through which the cooling air flows around an outer periphery of the stator, between the stator and the rotor, and inside the rotor, and a second passage provided in the stator frame, through which another cooling air flows that does not flow through the first passage; The rotating electric machine according to claim 1, wherein the second bearing is disposed adjacent to a flow passage through which the separate cooling air that has flowed through the second flow passage passes.

2. 2. The rotating electric machine according to claim 1, the plurality of inside air flow paths include a rotor core ventilation path through which the cooling air introduced into the interior of the rotor flows as first inside air, the air gap through which the cooling air introduced into the interior of the rotor flows as second inside air between the rotor and the stator, and an inside air flow path formed on the outer periphery of the stator through which the cooling air introduced into the interior of the rotor flows as third inside air, a rotor core ventilation passage, the air gap, and the internal air flow passage constitute the first flow passage.

3. 3. The rotating electric machine according to claim 2, A rotating electric machine characterized in that the flow path through which the other cooling air that has flowed through the second flow path passes is provided on the side of the second bracket to which the second bearing is mounted, and is a bearing-side flow path through which the other cooling air that has not been heated flows, and the other cooling air is introduced from the second flow path to the bearing-side flow path, and the second bearing is cooled with the other cooling air.

4. 4. The rotating electric machine according to claim 3, A rotating electric machine characterized in that a partition plate fixed to the second bracket is arranged on the inside air side of the second bracket, separating the bearing side flow path from an anti-bearing side flow path through which the cooling air passes, where the first inside air, the second inside air, and the third inside air join together.

5. 5. The rotating electric machine according to claim 4, The rotating electric machine according to claim 1, wherein the partition plate is fixed to the second bracket by a bolt, and a gasket is interposed in a fixed portion of the partition plate.

6. 6. A rotating electric machine according to claim 5, a piping for connecting the bearing-side flow passage to outside air, the piping directing the outside air to the bearing-side flow passage,

7. 6. A rotating electric machine according to claim 5, A rotating electric machine comprising: a fin provided on an outer surface of the second bracket.

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