JP4423271B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor used for driving a railway vehicle, for example, and more particularly to an electric motor for improving the cooling performance of a bearing portion.

When the motor is operated, the internal temperature rises due to heat generation, so heat is dissipated by a cooling fan, etc., but if the cooling performance is not sufficient, the lubrication grease of the bearing will deteriorate due to heat and the lubrication life will be shortened. It is necessary to replace the grease and maintenance work is required.
As a cooling method for the electric motor, there are an open type in which cooling air is introduced from the outside to cool each part in the electric motor, and a fully closed type in which the cooling air is not introduced into the electric motor. In the fully closed type, the cooling capacity is generally inferior to that of the open type, and in particular, the cooling performance of the bearing portion is required to be improved.

  As a conventional technique for improving the cooling performance of the bearing portion, for example, a fully-closed drive motor as shown in FIG. 7 is known. The figure shows an enlarged view of the bearing portion on the upper half and one side of the electric motor. A mirror cover 34 for supporting the first bearing 33 is provided on one end side of a cylindrical frame 32 having a stator core 31 with a coil mounted on the inner peripheral portion, and a second bearing is provided on the other end side (not shown). The shaft 36 of the rotor 35 is rotatably supported by both bearings. An end lid 37 is attached to the outside of the mirror lid 34 across the first bearing 33, and a collar 38 that rotates integrally with the shaft 36 is provided outside the end lid 37, and a fan action is provided on the outer periphery of the collar 38. For example, a gear-shaped groove 38a is formed as the cooling means having the above. When the collar 38 is rotated by the rotation of the shaft 36, the collar 38 is cooled to dissipate the heat of the bearing 33 to the outside, and at the same time, the mirror lid 34 is cooled by the wind generated in the direction of the arrow by the fan action of the groove 38a. The bearing 33 and the lubricating grease 39 are configured to be cooled (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-27708 (page 4-5, FIG. 1)

In the conventional motor, the collar can be expected to suppress the temperature rise of the bearing part, but the groove that acts as a collar fan on the outside of the mirror lid is provided on the outer periphery of the collar disk part. There was a problem that wind noise during rotation and the sound of the generated wind hitting the mirror lid were diffused as noise to the outside. In particular, when the cooling fins 34a are provided on the outer surface of the mirror lid in order to increase the cooling efficiency, there is a problem that the beat sound that hits the cooling fins 34a from the wind generated in the groove becomes a large noise source.
The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an electric motor that improves the cooling performance of the bearing portion and suppresses the generation of noise from the cooling structure portion. .

An electric motor according to the present invention includes a cylindrical frame, a stator provided at the center in the longitudinal direction of the frame, a rotor having a shaft at the center and disposed inside the stator, and both sides of the frame. Two brackets that close the opening, two bearings that support the shaft and that are supported one by one on the bracket, and a disc-shaped radiator that is fixed to the shaft near the outside of the machine of at least one bearing The heat radiator has a plurality of through holes formed in the circumferential direction in the vicinity of the outer periphery and a pressure formed by grooves formed radially from the through holes to the outer periphery on the side facing the bracket of the heat radiator. A generating mechanism is provided, and the surface of the bracket facing the radiator is an air inlet composed of a plurality of through holes in the circumferential direction around the rotation axis, and a concentric shape outside the air inlet. Formed with a plurality of through holes. The inboard side of the bracket, the air chamber to shut off the machine air communicated with the inlets and the exhaust port is provided with, between the inlet air port and the exhaust port of the outboard bracket, inlets And an annular shielding wall is provided with a small gap from the outer periphery of the radiator, and when the radiator rotates, the pressure generation mechanism causes a gap between the bearing side surface and the opposite surface. A pressure difference is generated so that outside air is introduced into the air chamber from the inlet and discharged from the outlet.

According to the electric motor of the present invention, the radiator having the pressure generating mechanism provided in the vicinity of the outer side of at least one of the two bearings supporting the shaft and the input provided on the bracket facing the radiator. A ventilation port including an air inlet and an exhaust port, an air chamber provided inside the machine of the bracket, and an air inlet and an exhaust port outside the machine of the bracket enclose the air inlet and the outer periphery of the radiator. When the radiator is rotated by the annular shielding wall provided with a minute gap , outside air is introduced from the inlet to the inside of the machine through the through hole of the radiator, and from the exhaust through the air chamber. Since the flow passage that discharges to the outside of the machine is formed, the bearing near the radiator is cooled by the radiator, the bracket is cooled by the air flowing through the flow passage, and the bearing held by the bracket is cooled. The cooling performance of the bearing The boss temperature rise can be efficiently suppressed.
In addition, when air outside the machine is introduced into the machine with a radiator, wind noise is generated due to the rotation of the radiator, but noise is diffused to the outside because the groove serving as the sound source is on the machine side. Can be suppressed, and noise can be reduced.
Furthermore, by providing a shielding wall, outside air can be efficiently taken into the inlet side from the radiator, and the groove that becomes a noise source when the radiator is rotated is concealed by the shielding wall, so that the noise is exposed to the outside. Leakage can be suppressed and noise reduction can be achieved.

Embodiment 1 FIG.
1 is a cross-sectional view of an electric motor according to Embodiment 1 of the present invention, and FIG. 2 is a partial cross-sectional view of a main part of FIG. In the figure, only the upper half side from the rotating shaft is shown, and the lower half side is omitted. Note that, as the electric motor, for example, a fully-closed drive electric motor used as a main electric motor for a vehicle will be described as an example.

In the figure, a stator 2 is provided at the center in the longitudinal direction of a cylindrical frame 1, and a rotor 4 having a shaft 3 at the center and rotating integrally is disposed inside the stator 2. Yes. The drive side 3 a of the shaft 3 is rotatably supported by the drive side bearing 5, and the counter drive side 3 b is rotatably supported by the counter drive side bearing 6. For example, in the case of a motor for a vehicle, the driving side 3a is connected to an axle (not shown) via a reduction gear (not shown) and drives a wheel (not shown) attached to the axle. The vehicle is configured to travel.
In the following description, when pointing to the left and right directions parallel to the rotation axis 7 at the center of the shaft 3, the side facing (or facing) the drive side 3a is directed to the "drive side" and directed to the counter drive side 3b (or The facing side will be referred to as the “non-driving side”.

The stator 2 includes a stator core 8 in which a large number of grooves are formed in an inner peripheral portion, and a stator winding 9 disposed in the grooves.
The rotor 4 includes a rotor core 10 having a large number of grooves formed on the outer periphery, a rotor conductor 11 disposed in the grooves, and an end ring 12 that connects ends of the rotor conductor 11. ing. The rotor core 10 is formed with a plurality of ventilation paths 10 a penetrating in the axial direction of the rotary shaft 7 in the circumferential direction.
An inner fan 13 is disposed on the drive side of the rotor 4 and is configured to rotate integrally with the shaft 3. A circulation duct 1 a that connects the driving side and the non-driving side is provided on the outer periphery of the frame 1.

  A drive side bracket 14 that holds the drive side bearing 5 and closes the end of the frame 1 is disposed on the drive side on one end side of the frame 1, and a counter drive side bearing 6 is provided on the non-drive side on the other end side. A non-driving side bracket 15 that holds and closes the end portion is provided. The brackets 14 and 15 and the frame 1 constitute a sealed machine in which the stator 2, the rotor 4, and the inner fan 13 are housed, and the flow of air outside the machine is blocked. A shaft lid 16 filled with lubricating grease is provided on the outside of the bearings 5 and 6 so as to support and fix both bearings 5 and 6 in cooperation with the brackets 14 and 15 and supply lubricating grease. It has become.

  A disk-like heat radiating body 17 that is fixed to the shaft 3 by, for example, fitting or the like and rotates integrally is provided near the outside of the drive side bearing 5, that is, outside the shaft lid 16. Similarly, a radiator 18 that rotates integrally with the shaft 3 is provided in the vicinity of the outer side of the non-drive side bearing 6, that is, outside the shaft lid 16. Since the structure of the radiators 17 and 18 and the bracket portion described below is the main part of the present invention, the structure of this portion will be described in more detail with reference to the enlarged sectional view in the vicinity of the drive side bearing 5 shown in FIG. explain. Since the driving side and the counter driving side are symmetrical and have substantially the same shape, only the driving side will be described, but the counter driving side is also the same.

  In FIG. 2, the heat radiating body 17 is provided with a pressure generating mechanism including a through hole 17b and a groove portion 17c. Details thereof will be described later. The drive-side bracket 14 facing the heat radiating body 17 is provided with an air inlet 14a composed of a plurality of holes and an exhaust port 14b composed of a plurality of holes on the outside thereof. The inlet and exhaust ports are collectively referred to as vents. An air chamber wall 20 is provided on the inner side of the drive side bracket 14 to form an air chamber 19 that communicates the inlet port 14a and the exhaust port 14b and blocks the air inside the unit. That is, the air chamber 19 is disposed on the inner side of the machine, but the air chamber is blocked from the in-machine air and communicates with the outside air. The air chamber wall 20 is processed by inclining the surface of a donut board-like plate material in a funnel shape, and the outer peripheral side and the inner peripheral side are fastened to the drive side bracket 14 with bolts. As long as it forms an air chamber that communicates with the in-machine air and is not limited to the shape shown in the figure.

FIG. 3 is a view of the central portion of the drive side bracket 14 as seen from the direction of arrow III in FIG. The inlet 14a and the outlet 14b will be described in more detail with reference to the drawings. The air inlets 14a are formed of a plurality of through holes formed at substantially equal intervals on the circumference of a circle having the rotation axis 7 of the shaft 3 as the center. The exhaust port 14b is composed of a plurality of through-holes formed on the outer peripheral side of a circle connecting the centers of the inlet ports 14a, concentrically with the circle, at substantially equal intervals. That is, D> d, where d is the diameter of the circle in which the inlet 14a is disposed and D is the diameter of the circle in which the exhaust 14b is disposed. The shape of the through hole is a long hole, but it may be a round hole or the like. Further, the number and the positional relationship in the circumferential direction are not limited to those in the figure, and may be appropriately determined in consideration of the strength of the bracket.
Note that the air inlets and the air outlets may not be arranged strictly on each circle, but may be arranged in a staggered manner along the circle, for example. In short, it is only necessary to configure the inlet port row on the inner side and the exhaust rear row on the outer side.

Next, details of the radiator 17 will be described with reference to FIG.
4A is a front view showing the heat radiating body 17 viewed from the drive side in FIG. 1, FIG. 4B is a side sectional view, and FIG. 4C is a rear view (counter drive side). As shown in (a), the heat dissipating body 17 is made of a disk-shaped plate material, and is provided with a shaft hole 17a that is inserted through the shaft 3 and fitted in the central portion thereof. A plurality (12 in the figure) of through holes 17b are formed at intervals. As shown in (c), the surface on the non-driving side (the surface facing the driving side bracket 14) has a U-shaped groove portion 17c having a width larger than the diameter of the through hole 17b, radially from the through hole 17b to the outer peripheral surface. Is formed. The through-hole 17b and the groove part 17c are connected as shown in the sectional view of (b). The through holes 17b do not necessarily have to be equally spaced.

The relationship between the diameter d of the circle in which the inlet port 14a of the drive side bracket 14 described above with reference to FIG. 3 is arranged, the diameter D of the circle in which the exhaust port 14b is arranged, and the outer diameter G of the radiator 17 is described. Is a size such that D>G> d. That is, when the state where the radiator 17 is combined with the electric motor is viewed from the drive side, only the exhaust port 14b is visible.
In addition, the shape of the radiator is an example, and here it is a disc shape, but the relationship between the size of the outer periphery and the inlet and outlet provided in the bracket is as described above, and the bracket If it does not touch, polygonal shape etc. may be sufficient, for example.

Similarly, the non-driving side bracket 15 is also formed with an air inlet 15a and an air outlet 15b, and an air chamber 19 is provided inside the machine.
Similarly, a through-hole 18b and a groove portion 18c are provided in the heat dissipating member 18 on the non-drive side.

Next, the operation will be described.
In the fully-closed electric motor configured as described above, the air in the machine sealed by the brackets 14 and 15 and the frame 1 is circulated through a ventilation path as indicated by a white arrow in FIG. That is, the air sucked by the rotation of the inner fan 13 is cooled while circulating through the circulation duct 1 a provided in the frame 1, returns from the opposite side to the inside, and again the air passage 10 a and the gap between the stator 2 and the rotor 4. To be introduced. Heat exchange is performed in this flow process, and the airframe is cooled.

On the other hand, as shown in FIG. 2, when the heat radiating body 17 is rotated by the rotation of the shaft 3, on the outside of the machine, the groove portion 17c cuts the wind with the rotation, and a pressure difference is generated between the driving side and the non-driving side. Due to the difference, an air flow that flows from the driving side to the non-driving side through the through hole 17b of the radiator 17 is generated. A part of the air flow hits the drive-side bracket 14 and directly cools the drive-side bracket 14, and the rest is introduced to the inside of the machine from an air inlet 14 a provided in the drive-side bracket 14 as indicated by an arrow in FIG. 2. Then, the air flows along the flow path that is discharged from the exhaust port 14b to the outside of the machine via the air chamber 19.
Thus, the groove 17c operates as a pressure generating mechanism that generates a pressure difference between the bearing-side surface and the machine-side surface when the heat radiating body 17 rotates. The pressure generating mechanism may be a protrusion instead of the groove. A shape that can generate a pressure difference when the radiator is rotated may be provided on at least one surface on the bearing side or the non-bearing side.

Since the radiator 17 is cooled by rotation, the heat accumulated in the machine is conducted through the shaft 3 and radiated from the radiator 17, but in addition to that, air directed toward the machine body by the radiator 17. By forming a flow path like the arrow that generates a flow, takes air outside the machine by the air flow, and discharges it outside the machine without being retained, the drive side bracket 14 is efficiently cooled by the air flow Therefore, the drive side bearing 5 held by the drive side bracket 14 and the lubricating grease filled in the shaft side end of the drive side bracket 14 and the shaft lid 16 are cooled.
In addition, since the air chamber wall 20 that forms the air chamber 19 inside the machine is formed of a thin plate, the air in the machine that has risen in temperature due to the heat generated on the rotor 4 side is heat-exchanged by the air chamber wall 20. The effect of lowering the temperature can be expected.
Further, the heat generated in the stator 2 is transmitted to the drive side bearing 5 through the frame 1 and the drive side bracket 14, but the bracket is cooled in the air chamber 19 in the middle, so that the heat is transmitted to the drive side bearing 5. Heat is suppressed.

  Further, when the heat radiating body 17 rotates, the groove portion 17c of the heat radiating body 17 cuts the wind by the rotation, so that a wind noise is generated at this time. This sound is transmitted to the surroundings as noise, but in the heat dissipating body 17 of the present invention, the groove portion 17c as a sound source is opposed to the airframe side and is not visible from the outside of the airframe. It is possible to suppress the noise from being emitted to the surroundings.

In the above description, the case where the cooling structure including the air inlet, the exhaust port, and the air chamber formed in the radiator and the bracket is provided on both the driving side and the non-driving side has been described. It may be provided only. For example, in the case of an external fan type electric motor in which an outer fan is provided on one of the shafts and the fuselage is cooled by the outer fan, the bearing arranged on the outer fan side has a function that the outer fan functions as a cooling medium. Since it is cooled, the cooling structure of the present invention may be provided only on the bearing side where the outer fan is not provided.
Also, among the vents, the axial center side is the inlet and the outer peripheral side is the exhaust port, but the direction in which the pressure difference is generated by the rotation of the radiator is reversed, the axial side is the exhaust port, and the outer peripheral side The air passage may be in the opposite direction.
Moreover, although the electric motor was demonstrated as a fully-closed type motor, it was not necessarily limited to a fully-closed type motor. The fully-closed motor is generally inferior in cooling performance compared to the open type that introduces cooling air into the machine, so it will be more effective if the cooling structure of the present invention is applied. The effect which suppresses the temperature rise of a bearing part can be anticipated.

  As described above, according to the invention of the present embodiment, the radiator provided in the vicinity of the outside of the at least one bearing of the driving side bearing or the non-driving side bearing and the vent provided in the bracket opposed to the radiator. When the heat sink is rotated by the air inlet and exhaust ports and the air chamber provided inside the machine, the outside air is introduced into the machine from the air inlet through the through hole of the heat sink. Since the flow passage that discharges to the outside of the machine from the exhaust port via is formed, the bearing portion near the radiator is cooled by the radiator, and the bracket that faces the radiator is cooled by the air flowing through the passage, Since the bearing part hold | maintained with the bracket is cooled, the cooling performance of a bearing part can be improved and a temperature rise can be suppressed efficiently. Therefore, the bearing and the lubricating grease can be kept at a stable temperature.

  In addition, when air outside the machine is introduced into the machine with a radiator, wind noise is generated due to the rotation of the radiator, but noise is diffused to the outside because the groove serving as the sound source is on the machine side. Can be suppressed, and noise can be reduced.

Embodiment 2. FIG.
FIG. 5 is a partial cross-sectional view showing a main part of an electric motor according to Embodiment 2 of the present invention. The part corresponding to FIG. 2 of Embodiment 1 is shown, and an equivalent part attaches | subjects the same code | symbol and abbreviate | omits description. In the following description, the description will focus on parts different from FIG. Further, the entire configuration of the motor other than that shown in FIG. 5 is the same as that of FIG.

  As shown in FIG. 5, the first embodiment is different from the first embodiment in the radial direction of the wall surface on the outer side of the drive side bracket 14 between the inlet port 14a and the exhaust port 14b formed concentrically. This is the point that an annular shielding wall 21 protruding outward is provided. On the inner diameter side, a smooth curved surface 21a that curves toward the axial center is formed. As in the first embodiment, a heat radiator 17 that is integrally coupled to the shaft 3 is provided in the vicinity of the outer side of the drive side bearing 5. The shape of the heat radiating body 17 is the same as that of FIG. However, the outer diameter is set such that a minute gap is formed with the inner diameter side of the shielding wall 21 within a range that does not hinder the rotation of the radiator 17, and the heat radiator 17 is disposed on the inner diameter side of the shielding wall 21. . Further, it is desirable that the driving side end face of the shielding wall 21 and the driving side end face of the heat dissipating body 17 be substantially the same plane as shown in the figure.

Next, the operation will be described.
Since the radiator 17 is cooled by rotation, the heat generated by the rotor 4 in the machine is transmitted through the shaft 3 and radiated from the radiator 17. At the same time, as described in the first embodiment, due to the action of the through hole 17b and the groove portion 17c of the heat radiating body 17, the outside air is drawn from the drive side through the through hole 17b to the non-drive side, and the air inlet 14a- The air flow which flows through the flow path of the air chamber 19-exhaust port 14b is generated. The drive side bracket 14 is cooled by the air flow, and the drive side bearing 5 and the lubricating grease held thereon are cooled. Although these cooling mechanisms are the same as those in the first embodiment, the air sucked from the through hole 17b is efficiently introduced into the air inlet 14a with little leakage to the outside by providing the shielding wall 21. In addition, the exhaust is blocked from entering the inside through the gap between the drive side bracket 14 and the radiator 17. Furthermore, wind noise is generated when the air is agitated in the groove portion 17c when the heat radiator 17 rotates. However, since the noise source is completely hidden inside, it is effective that noise due to wind noise leaks to the outside. Can be suppressed.
In addition, the shielding wall may not necessarily be an annular shape but may be a polygon. If it is arranged with a certain distance between the radiator and the radiator so that it does not come into contact with the rotating radiator, it can block the air that enters the inlet and the air that exits the outlet. It can be anything.

In FIG. 5, the shape on the inner diameter side of the shielding wall 21 has a curved surface 21a toward the axial center side. However, this smoothes the flow path to reduce resistance, and provides a cooling effect and noise suppression effect. This is a contrivance for further enhancement, and is not limited to the curved surface in the figure, and does not necessarily require a curved surface. For example, if both the inner diameter side and the outer diameter side are formed in a cylindrical shape parallel to the rotating shaft 7, the effect is slightly reduced, but the production of the shielding wall is simplified.
Moreover, although the case where the shielding wall 21 was formed integrally with the drive side bracket 14 was shown in the figure, it may be produced separately and combined.

As described above, according to the invention of the present embodiment, in the radial direction of the bracket facing the radiator, an annular shielding wall is provided on the outer wall surface between the inlet and the outlet. Since the radiator is arranged on the inner diameter side of the shielding wall and the outer diameter is sized so as to form a small gap with the inner diameter of the shielding wall, in addition to the effects of the first embodiment, the outside air is efficiently introduced from the radiator. It can be taken into the side of the mouth, and since the groove serving as a noise source is concealed by the shielding wall at the time of rotation of the radiator, noise can be prevented from leaking to the outside, and noise can be reduced.
In addition, by making the inner peripheral surface of the shielding wall into a curved surface, the outside air taken in by the radiator can be smoothly guided to the inlet, thereby reducing the fluid resistance and further improving the cooling effect and the noise suppression effect. Can do.

Embodiment 3 FIG.
6 is a partial cross-sectional view showing a main part of an electric motor according to Embodiment 3 of the present invention. It is a part corresponding to FIG. 5 of Embodiment 2, and an equivalent part attaches | subjects the same code | symbol, description is abbreviate | omitted and it demonstrates centering on difference. The entire configuration of the motor other than that shown in FIG. 6 is the same as that of FIG.

  FIG. 2 is a diagram of a second embodiment in which a radiator 17 is provided in the vicinity of the drive-side bearing 5, an intake port 14 a, an exhaust port 14 b and an air chamber 19 are provided in the drive-side bracket 14 In the present embodiment, a reflux prevention ring 22 is further provided at the outer end of the shielding wall 21 in the present embodiment. The reflux prevention ring 22 is a thin disk that is formed by pressing and forming an inclined surface that spreads toward the outer diameter side on the drive side, but is not limited to this, and it is rotated without an inclined surface. A cylindrical shape parallel to the shaft 7 may be used.

Next, the operation of the reflux prevention ring 22 will be described.
The air flow path when the radiator 17 rotates is as shown by arrows in the figure. The air sucked from outside the machine is heat-exchanged in the air chamber 19 to rise in temperature, and is discharged at a high temperature. The reflux prevention ring 22 serves to keep the high-temperature exhaust as far away from the through hole 17b of the radiator 17 as possible, and prevents the exhaust from returning to the through hole 17b of the radiator 17 again.
In addition, when the air inlet and the air outlet are opposite to those shown in the figure and the air inlet is provided outside the shielding wall, a similar anti-reflux ring is provided so that the machine passes through the through hole of the air outlet and the radiator. It is possible to prevent the air exhausted outside from returning to the inlet. The reflux prevention ring may be formed integrally with the shielding wall.

  As described above, according to the invention of the present embodiment, the reflux prevention ring that prevents the exhaust from the exhaust port from heading toward the through hole of the radiator is provided at the outer end of the shielding wall. In addition to the effect of the second aspect, it is possible to prevent the high-temperature exhaust discharged from the exhaust port from going again to the through hole of the heat radiating body, thereby further enhancing the cooling effect.

It is sectional drawing which shows the electric motor in Embodiment 1 of this invention. It is a principal part expanded sectional view of FIG. It is a top view which shows the center part of the drive side bracket of FIG. It is a figure which shows the heat radiator of FIG. It is a principal part expanded sectional view of the electric motor in Embodiment 2 of this invention. It is a principal part expanded sectional view of the electric motor in Embodiment 3 of this invention. It is sectional drawing of the conventional fully-closed drive motor.

Explanation of symbols

1 Frame 1a Circulating duct 2 Stator 3 Shaft 3a Driving side 3b Non-driving side
DESCRIPTION OF SYMBOLS 4 Rotor 5 Drive side bearing 6 Counter drive side bearing 7 Rotating shaft 8 Stator core 9 Stator winding 10 Rotor core 10a Ventilation path 11 Rotor conductor 12 End ring 13 Inner fan 14 Drive side bracket 14a, 15a Inlet air Port 14b, 15b Exhaust port 15 Counter drive side bracket 16 Shaft lid 17, 18 Radiator 17a Shaft hole 17b, 18b Through hole 17c, 18c Groove portion 19 Air chamber 20 Air chamber wall 21 Shielding wall 21a Curved surface 22 Reflux prevention ring

Claims (3)

A cylindrical frame,
A stator provided in the longitudinal center of the frame;
A rotor having a shaft in the center and disposed inside the stator;
Two brackets closing the openings on both sides of the frame;
Two bearings that support the shaft and are held by the bracket one by one;
A disk-shaped heat radiator fixed to the shaft in the vicinity of the outside of the machine of at least one bearing,
The heat radiating body includes a plurality of through holes formed in a circumferential direction near the outer periphery, and a pressure generation formed by grooves formed radially from the through holes to the outer periphery on the side facing the bracket of the heat radiating body. Mechanism is provided,
On the surface of the bracket facing the heat radiator, an air inlet composed of a plurality of through holes in the circumferential direction around the rotation axis, and a plurality of through holes concentrically outside the air inlet An air chamber configured to communicate with the air inlet and the exhaust port and shut off from the air inside the device is provided on the inner side of the bracket.
An annular shielding wall is provided between the upper entry air vent on the outside of the bracket and the exhaust vent, surrounding the air inlet and having a small gap from the outer periphery of the radiator. ,
When the radiator is rotated, a pressure difference is generated between the bearing-side surface and the opposite surface by the pressure generating mechanism, and external air is introduced into the air chamber from the inlet, and the exhaust An electric motor characterized by being discharged from the mouth. In claim 1 the electric machine described in the motor, wherein the inner peripheral side of the shielding wall is formed in a curved surface. In claim 1 the electric machine described in the so prevent the flow of air between the shielding walls of the through hole provided in the exhaust port provided on the outside and the heat radiator, outboard of the shielding wall An electric motor comprising a reflux prevention ring.

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