JP2010028918A - Cooling structure of electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of an electric motor for further prolonging the service life of a brush by further suppressing an increase in the temperature of the brush. <P>SOLUTION: Provided is the cooling structure of an electric motor 1 equipped with a yoke 2, an end bracket 17 for covering one end of the yoke 2, and an armature 3 disposed in the inside of the yoke 2 and freely rotatably supported on the end bracket 17; and a brush slidably contacting a commutator provided on the armature 3 and feeding power is disposed on the inner surface of the end bracket 17. In the cooling structure, a first ventilating hole 25 is formed on an end portion 2b forming the bottom surface of the yoke 2, and a second ventilating hole 27 is formed near the brush of the end bracket 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling structure for an electric motor, and more particularly to a cooling structure for a fan motor for an automobile.

Generally, an electric motor with a brush used as a fan motor for an automobile has a configuration in which an armature in which an armature coil is wound inside a cylindrical yoke with a permanent magnet attached to an inner peripheral surface is rotatably arranged. In many cases. The armature has an armature core that is externally fixed to the rotating shaft. A plurality of teeth that are long in the axial direction are formed on the armature core, and a coil is wound around the teeth.
Each coil is connected to a plurality of segments of a commutator attached to the rotating shaft. The commutator is for supplying current to the coil and performing rectification, and the plurality of segments and the brush are in sliding contact with each other.

The brush is electrically connected to an external power source and applies a voltage to the segment. The brush is housed in the brush holder so as to be movable back and forth with respect to the commutator (segment). The brush holder is fixed to a bracket that covers the opening of the yoke via a holder stay.
When the brush applies a voltage to the segment, current is supplied to the coil and a magnetic field is formed in the armature core. And a rotating shaft rotates by the magnetic attractive force and repulsive force which arise between this magnetic field and a permanent magnet. As a result of this rotation, the segments in sliding contact with the brush are sequentially changed and mechanically rectified, and the armature core continuously rotates.

Here, in the electric motor with a brush, as the armature rotates, the brush repeatedly contacts and separates from the segment. For this reason, when the voltage between the segments is large, when the brush is separated from the segment, the electromagnetic energy stored in the coil is released, so that discharge may occur between the brush and the segment.
When a discharge occurs between the brush and the segment, the brush and the segment are subjected to discharge wear, the brush temperature rises, and the brush wear may be accelerated.

For this reason, various techniques for reducing the voltage between segments and suppressing the increase in brush temperature have been proposed. For example, the coil wound around the teeth has a five-phase (U, V, W, X, Y phase) structure, so that it is more segmented than an electric motor having a three-phase (U, V, W phase) coil. A technique for reducing the inter-voltage is known (see, for example, Patent Document 1).
JP 2008-136343 A

  However, in the above-described prior art, even if the voltage between segments is reduced, the temperature inside the motor rises, that is, the brush temperature rises as the coil temperature rises or the motor operating environment temperature rises. It is difficult to effectively suppress an increase in brush temperature. For this reason, there is a problem that there is a limit in extending the life of the brush.

  Therefore, the present invention has been made in view of the above-described circumstances, and further provides a cooling structure for an electric motor that can further suppress an increase in brush temperature and can extend the life of the brush. Is.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a yoke having a cylindrical portion, an end bracket that covers one end of the yoke, and an inner side of the yoke that is rotatable on the end bracket. An end portion of the yoke constituting the bottom surface of the yoke in the cooling structure of the electric motor, wherein the end bracket is provided with a brush that slidably contacts the commutator provided on the armature and that supplies power to the inner surface of the end bracket. A first ventilation hole is formed in the portion, and a second ventilation hole is formed in the vicinity of the brush of the end bracket.
In this case, as in the invention described in claim 2, a recess for storing the brush may be formed on the inner surface of the end bracket, and the second ventilation hole may be formed on the peripheral surface of the recess. .
By comprising in this way, the ventilation path through which air passes along an axial direction can be formed in a yoke inside. Moreover, since a brush is provided in the middle of a ventilation path, it becomes possible to suppress the temperature rise of a brush effectively. Furthermore, since the 2nd ventilation hole formed in the end bracket is formed in the vicinity of a brush, the temperature rise of a brush can be suppressed more effectively.

According to a third aspect of the present invention, the end bracket is provided with a plurality of stays for fixing to an external device, and the positions where the plurality of stays are arranged are avoided in the circumferential direction. It is characterized by being set to.
With this configuration, even when the stay is provided in the end bracket, the stay does not interfere when the second ventilation hole is formed in the end bracket.

  According to the first and second aspects of the present invention, it is possible to form a ventilation path through which air passes along the axial direction inside the yoke. Moreover, since a brush is provided in the middle of a ventilation path, it becomes possible to suppress the temperature rise of a brush effectively. Furthermore, since the 2nd ventilation hole formed in the end bracket is formed in the vicinity of a brush, the temperature rise of a brush can be suppressed more effectively. For this reason, it is possible to further extend the life of the brush.

  According to the third aspect of the present invention, even when the stay is provided on the end bracket, the stay does not get in the way when the second ventilation hole is formed in the end bracket. For this reason, it becomes possible to form a 2nd ventilation hole easily in an end bracket, and can aim at reduction of manufacturing cost.

Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the electric motor 1 with a brush is a so-called DC brush motor, and is used as a fan motor for cooling a radiator of an automobile. The electric motor 1 includes an armature 3 that is rotatably provided in a bottomed cylindrical yoke 2 and covers an opening 2 c of the yoke 2 with an end bracket 17. And the electric motor 1 is attached to the radiator of the motor vehicle with the rotating shaft 5 of the armature 3 along the horizontal direction.

Eight permanent magnets 4 are juxtaposed along the circumferential direction on the inner surface of the peripheral wall 2a that is the cylindrical portion of the yoke 2. A plurality (twelve in this embodiment) of first vent holes 25 are formed at equal intervals in the circumferential direction on the end portion (bottom surface) 2b of the yoke. The first ventilation hole 25 is for taking air into the electric motor 1 and cooling the electric motor 1. Each first ventilation hole 25 is provided with a flange 26 for making it difficult for water to enter the electric motor 1. Each flange portion 26 is formed so as to rise obliquely downward from the upper half edge of the first ventilation hole 25, that is, from the upper half in gravity.
Further, a boss portion 10 is formed in the end portion (bottom portion) 2b of the yoke 2 at a substantially radial center. The boss portion 10 is formed with an insertion hole 11 for inserting the rotation shaft 5 of the armature 3 and a bearing 12 for rotatably supporting one end side of the rotation shaft 5.

  The armature 3 includes an armature core 6 that is externally fitted and fixed to the rotating shaft 5, an armature coil 7 that is wound around the armature core 6, and a commutator 13 that is disposed on the other end side of the rotating shaft 5. . The armature core 6 is formed by laminating a plurality of metal plates in the axial direction or press-molding soft magnetic powder.

  As shown in FIGS. 3 and 4, the armature core 6 has a substantially annular rotary shaft fixing portion 61 that is fitted and fixed to the rotary shaft 5. The rotary shaft 5 is press-fitted and fixed in an insertion hole 61 a formed in the rotary shaft fixing portion 61. An outer annular portion 62 formed concentrically with the rotation shaft fixing portion 61 is provided on the outer side in the radial direction of the rotation shaft fixing portion 61. Between the rotary shaft fixing portion 61 and the outer annular portion 62, five spoke portions 63 are provided at equal intervals in the circumferential direction so as to extend over both the portions 61 and 62. That is, the armature core 6 is formed with five through-holes 64 penetrating in the axial direction and substantially fan-shaped in plan view in the axial direction by the rotating shaft fixing portion 61, the outer annular portion 62, and the spoke portion 63. become.

  On the radially outer side of the outer annular portion 62, ten teeth 36 that are substantially T-shaped in plan view in the axial direction are radially formed at equal intervals along the circumferential direction. Between adjacent teeth 36, a dovetail slot 37 is formed. Ten slots 37 extend along the axial direction, and are formed at equal intervals along the circumferential direction. An enamel-coated winding 38 is passed through the slot 37, and the winding 38 is wound around the tooth 36 by concentrated winding via an insulator (not shown). As a result, a plurality of armature coils 7 are formed on the outer periphery of the armature core 6.

  The armature core 6 is formed with substantially circular recesses 30 in the axial center in the radial center. Of these recesses 30, 30, a ring-shaped guide portion 66 is fitted into the recess 30 formed on the commutator 13 side. The guide portion 66 is for preventing the crossover portion of the winding 38 routed between the teeth 36 from interfering with the riser 43 of the commutator 13 described later.

The commutator 13 includes a resin mold body 40 that is externally fixed to the rotary shaft 5 and formed in a columnar shape, 20 segments 41 that are exposed on the outer peripheral surface of the resin mold body 40, and the resin mold body 40. And the short-circuit member 42 that short-circuits the same potential segments of the 20 segments 41.
The segment 41 is made of a plate-like metal piece that is long in the axial direction, and is fixed in parallel at equal intervals along the circumferential direction while being insulated from each other. Among these segments 41, five segments 41 that are present at equal intervals in the circumferential direction are integrally formed with a riser 43 that is folded back to the outer diameter side at the end on the armature core 6 side.

The riser 43 is for connecting the armature coil 7 to the segment 41. The winding start end and the winding end end of the winding 38 drawn from the armature coil 7 are respectively wound around and fixed by fusing. It has become so. Thereby, the segment 41 and the armature coil 7 corresponding to this are electrically connected.
The short-circuit member 42 is formed by laminating a plurality of short-circuit rings 46 at intervals in the axial direction.
That is, the same potential segments are short-circuited by one short ring 46.

  Here, the electric motor 1 of the present embodiment has eight permanent magnets 4 (magnetic poles), ten slots 37, and twenty segments 41, and windings 38 are concentrated on the teeth 36 of the armature core 6. It is an 8-pole 10-slot 20-segment 5-phase direct current motor wound around. Therefore, every fourth segment 41 is the same potential segment. Accordingly, since five sets of equipotential segments are formed, the short-circuit member 42 is composed of five short-circuit rings 46.

As shown in FIGS. 1 to 3, the end bracket 17 is made of metal and is formed in a substantially disc shape, and a convex portion 15 that protrudes outward is formed in a large part of the center. . By forming the convex portion 15, the inner surface side becomes concave. The inner surface side of the concave convex portion 15 functions as an accommodating concave portion 16 for accommodating a brush 22 described later.
A boss portion 18 is formed on the end portion (bottom portion) 15a of the convex portion 15 so as to protrude further outward due to a step at a substantially radial center. A bearing 19 for rotatably supporting the other end side of the rotating shaft 5 is press-fitted and fixed to the boss portion 18.

Three stays 9 extending outward are provided on the outer peripheral side of the end bracket 17. This stay 9 is used when fixing the electric motor 1, and is provided with a bolt hole 9 a that is formed by burring and projects toward the side opposite to the yoke 2.
A holder stay 20 is attached to the storage recess 16 of the end bracket 17. The holder stay 20 is made of resin and formed in a substantially disc shape, and four brush holders 21 are fixed to the inner surface.

  As shown in FIG. 3 and FIG. 5, the brush holder 21 is formed in a rectangular parallelepiped box shape by true casting or the like, and is arranged radially so that the longitudinal direction is along the radial direction. The brush holder 21 is provided with a brush 22 that is urged via a coil spring 23 so that the brush 22 can advance and retreat relative to the commutator 13. The tips of the brushes 22 are urged by the coil springs 23 and are in sliding contact with the segments 41 of the commutator 13.

  The brush 22 is configured to include two sets of an anode side brush 22a and a cathode side brush 22b. The anode-side brush 22a and the cathode-side brush 22b are arranged in such a state that the same-polarity-side brushes 22 are spaced apart in the circumferential direction by a mechanical angle of 90 °. They are arranged with a mechanical angle of 135 ° and on the other hand a mechanical angle of 45 ° in the circumferential direction.

  That is, in this embodiment, since the eight permanent magnets 4 are arranged at equal intervals in the circumferential direction, the brushes 22 on the same pole side are arranged with an electrical angle of 360 ° in the circumferential direction, The brushes 22 on the opposite pole sides are arranged in a state where they are spaced apart in the circumferential direction by an electrical angle of 180 °. And the brushes of the same polarity side are in a state of being concentrated at one place. That is, the anode side brushes 22a and 22a are arranged in the right half of the holder stay 20 (the right half of the paper surface in FIG. 5), while the cathode side brushes 22b and 22b are the left half of the holder stay 20 (the paper surface in FIG. 5). The left half) is placed.

  In addition, the holder stay 20 is provided with a power feeding unit 70 at the approximate center between the anode-side brush 22a and the cathode-side brush 22b that are spaced apart from each other by a mechanical angle of 135 °. The power supply unit 70 supplies power to the anode side brush 22a and the cathode side brush 22b, and is electrically connected to an external power source (not shown). Furthermore, one end of an anode-side terminal 71 and a cathode-side terminal 72 that are insert-molded in the holder stay 20 are connected to the power supply unit 70.

The anode-side terminal 71 is for connecting the power feeding unit 70 and the anode-side brushes 22a and 22a, and has an exposed portion 74 in the vicinity of the two anode-side brushes 22a and 22a. The pigtail 73 of the anode-side brush 22a is connected to the exposed portion 74 of the anode-side terminal 71, thereby being electrically connected to the power feeding portion 70.
On the other hand, the cathode side terminal 72 is for connecting the power supply unit 70 and the cathode side brushes 22b and 22b, and has an exposed portion 75 in the vicinity of the two cathode side brushes 22b and 22b. The pigtail 73 of the cathode-side brush 22b is connected to the exposed portion 75 of the cathode-side terminal 72, thereby being electrically connected to the power feeding portion 70.

Then, the electric power of the external power source is supplied to the armature coil 7 via the power feeding unit 70, the terminals 71 and 72, the pigtail 73, the brush 22, and the segment 41.
With such a configuration, the holder stay 20 is attached to the storage recess 16 of the end bracket 17 so that the power feeding unit 70 is located on the gravity lower side. That is, the two brushes 22 on the opposite pole sides, which are arranged in a state where the mechanical angle is 45 ° in the circumferential direction, are located on the gravity upper side.

  Here, as shown in FIGS. 1, 2, and 6, the end bracket 17 is formed with a plurality of second ventilation holes 27 on the peripheral surface 15 b of the convex portion 15. The second ventilation hole 27 is for taking air into the electric motor 1 in the same manner as the first ventilation hole 25 formed in the end portion 2 b of the yoke 2. The 2nd ventilation hole 27 makes two 2nd ventilation holes 27 and 27 adjacently arranged in parallel as one group, and forms this group at three equal intervals in the circumferential direction.

The second ventilation holes 27 are long in the circumferential direction and are formed in a substantially rectangular shape in plan view. When the second ventilation holes 27 are arranged adjacent to each other, one set of the second ventilation holes 27 is provided. , 27 is set to be slightly larger than about 1/8 of the circumferential length of the peripheral surface 15b of the convex portion 15 (see the two-dot chain line in FIG. 6).
The second ventilation holes 27 formed in this way are arranged at three equal intervals in the circumferential direction so that one of them is positioned above gravity. That is, each second ventilation hole 27 is formed in the vicinity of each brush 22.

  Further, as shown in FIG. 6, the positions of the three stays 9 provided on the outer peripheral side of the end bracket 17 are set at positions where the formation positions of the second ventilation holes 27 are avoided in the circumferential direction. That is, since the pair of second ventilation holes 27 are formed at three equal intervals in the circumferential direction, the stay 9 is arranged in the circumferential direction so as to avoid the formation positions of the second ventilation holes 27 in the circumferential direction. It is provided at equal intervals.

Next, the flow of air around the electric motor 1 will be described with reference to FIGS. 1 and 6.
In the electric motor 1, the first ventilation hole 25 is formed in the end portion 2 a of the yoke 2, and the second ventilation hole 27 is formed in the peripheral surface 15 b of the convex portion 15 of the end bracket 17. The air flowing into the electric motor 1 from the vent hole 25 is exhausted from the second vent hole 27 or returned to the first vent hole 25 and exhausted from here (see arrows in FIGS. 1 and 6). ).

  On the other hand, the air flowing into the electric motor 1 from the second ventilation hole 27 is exhausted from the first ventilation hole 25 or returned to the second ventilation hole 27 and exhausted from here (FIGS. 1 and 2). (See arrow in 6). That is, the electric motor 1 is provided with a ventilation path TL along the axial direction. And each brush 22 will be in the state arrange | positioned in the middle of the ventilation path TL of the electric motor 1. FIG.

Therefore, according to the above-mentioned embodiment, the air which flowed in from the outside sufficiently hits each brush 22 and can efficiently exchange heat with the outside air. For this reason, it becomes possible to suppress the temperature rise of each brush 22 effectively, and the lifetime improvement of a brush can be aimed at.
Further, since each second ventilation hole 27 is formed in the vicinity of each brush 22, it is possible to more efficiently apply outside air to each brush 22. For this reason, the temperature rise of a brush can be suppressed more effectively and it becomes possible to aim at the lifetime improvement of a brush more.

  Here, for example, when the first ventilation hole 25 is formed in the end portion 2a of the yoke and the second ventilation hole 27 is not formed in the end bracket 17, the air flowing in from the first ventilation hole 25 is The air is exhausted from the first ventilation hole 25 again almost without passing through the location where the brush 22 is disposed. For this reason, since the brush 22 is not sufficiently exposed to air, heat exchange with the outside air cannot be performed sufficiently, and therefore it is difficult to effectively suppress the temperature increase of the brush 22.

This will be described more specifically with reference to FIGS.
In FIG. 7, when the vertical axis is the temperature (° C.) of the brush 22 and the horizontal axis is neither the first ventilation hole 25 nor the second ventilation hole 27 (sealed type), only the first ventilation hole 25 is formed. It is a graph comparing the temperatures of the brushes 22 attached to each of the three cases (semi-open type), the case where both the first vent hole 25 and the second vent hole 27 are formed (full open type).
As shown in the figure, it can be confirmed that the temperature of the brush 22 attached to the semi-open type is lower than the sealed type. Furthermore, it can be confirmed that the temperature of the brush 22 attached to the full open type is lower than the semi open type.

FIG. 8 is a graph in which the usable time (h) of the brush 22 is plotted on the vertical axis, and the usable time of the attached brush 22 is compared with the horizontal axis on the three types of sealed type, semi-open type, and full open type. is there.
As shown in the figure, it can be confirmed that the usable time of the brush 22 attached to the semi-open type is longer than the sealed type. Furthermore, it can be confirmed that the usable time of the brush 22 attached to the full open type is longer than the semi open type.
Therefore, it is possible to extend the life of the brush 22 by reducing the temperature of the brush 22.

  Further, according to the above-described embodiment, the stay 9 of the end bracket 17 is provided at three equal intervals in the circumferential direction so as to avoid the formation position of the second ventilation hole 27 in the circumferential direction. When the second ventilation hole 27 is formed, the stay 9 does not get in the way. For this reason, it becomes possible to form the 2nd ventilation hole 27 in the end bracket 17 easily, and can aim at reduction of manufacturing cost.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
In the above-described embodiment, the anode-side brush 22a and the cathode-side brush 22b are arranged in a state where the brushes 22 on the same polarity side are spaced apart in the circumferential direction by a mechanical angle of 90 °. A case has been described in which the brush 22 is disposed with a mechanical angle of 135 ° on the one hand and a mechanical angle of 45 ° on the other hand and spaced in the circumferential direction. However, the present invention is not limited to this, and the brushes 22 on the opposite pole sides may be arranged with an electrical angle of 180 ° in the circumferential direction.

Another example is shown in FIG. As shown in the figure, the arrangement of the brushes 22 is replaced with that shown in FIG. 5, and the anode-side brush 22a and the cathode-side brush 22b are spaced apart in the circumferential direction by 180.degree. You may arrange | position in the state, and may arrange | position the brush 22 of the different polarity side in the state which left the space | interval in the circumferential direction of mechanical angle 135 degrees on the one hand, and mechanical angle 45 degrees on the other side.
In this case, the holder stay 20 has a pair of power feeding portions 90a and 90b, that is, a first center, approximately at the center between the anode-side brush 22a and the cathode-side brush 22b, which are disposed at a mechanical angle of 135 °. A power feeding unit 90a and a second power feeding unit 90b are provided.

The first power supply unit 90a (the lower power supply unit in FIG. 9) has a set of first anode side terminals for connecting the first set of anode side brush 22a and cathode side brush 22b to the first power supply unit 90a. 91a and one end of the first cathode side terminal 92a are connected.
The first anode-side terminal 91a is for connecting the first power feeding portion 90a and one anode-side brush 22a (the anode-side brush 22a arranged at the lower right in FIG. 9), and the corresponding anode side An exposed portion 94 is provided in the vicinity of the brush 22a. The corresponding pigtail 73 of the anode brush 22a is connected to the exposed portion 94 of the first anode terminal 91a, thereby being electrically connected to the first power feeding portion 90a.

  On the other hand, the first cathode-side terminal 92a is for connecting the first power feeding section 90a and one cathode-side brush 22b (the cathode-side brush 22b arranged at the lower left in FIG. 9), and corresponds. An exposed portion 95 is provided in the vicinity of the cathode side brush 22b. The corresponding pigtail 73 of the cathode-side brush 22b is connected to the exposed portion 95 of the first cathode-side terminal 92a, thereby being electrically connected to the first power feeding portion 90a.

  In the second power feeding section 90b (upper power feeding section in FIG. 9), a set of second anode side terminals for connecting the pair of anode side brush 22a and cathode side brush 22b to the second power feeding section 90b. 91b and one end of the second cathode side terminal 92b are connected. Since the second anode side terminal 91b and the second cathode side terminal 92b are formed in the same manner as the first anode side terminal 91a and the first cathode side terminal 92a described above, description thereof is omitted.

According to such a configuration, two sets of the anode side brush 22a and the cathode side brush 22b can be provided. In addition to this, in the electric motor 1 having four brushes 22 having eight magnetic poles, the layout variations of the brushes 22 can be increased.
Further, since the brushes 22 are arranged symmetrically with respect to the rotation axis 5, the weight balance of the electric motor 1 can be further improved, and the brushes are arranged opposite to each other. Thus, the balance of the contact pressure to the commutator can be optimized.

  Here, even if each brush 22 is arranged at a point-symmetrical position about the rotation axis 5, the second ventilation hole 27 is formed in the vicinity of the brush 22. That is, in FIG. 9, the second ventilation hole 27 is formed outside the brush 22 in a range indicated by a two-dot chain line. At this time, the three stays 9 provided on the outer peripheral portion side of the end bracket 17 may be provided at three locations so as to avoid the formation location of the second ventilation hole 27 in the circumferential direction.

It is a side view of the electric motor in the embodiment of the present invention. It is a top view of the electric motor in the embodiment of the present invention. It is a longitudinal section showing the composition of the electric motor in the embodiment of the present invention. It is a top view of the electric motor of the state which removed the end bracket in embodiment of this invention. It is a layout drawing of the brush in the embodiment of the present invention. It is a layout diagram of the brush and stay in the embodiment of the present invention. It is the graph which compared the temperature of the brush in embodiment of this invention. It is the graph which compared the usable time of the brush in embodiment of this invention. It is a layout drawing of the brush in other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor 2 Yoke 2a Perimeter wall (cylinder part)
2b End part 3 Armature 4 Permanent magnet 5 Rotating shaft 7 Armature coil (coil)
9 Stay 13 Commutator 15 Convex part 16 Concave concave part (concave part)
17 End bracket 22 Brush 22a Anode side brush 22b Cathode side brush 25 First ventilation hole 27 Second ventilation hole 37 Slot 41 Segment

Claims (3)

A yoke having a cylindrical portion;
An end bracket that covers one end of the yoke;
An armature disposed inside the yoke and rotatably supported by the end bracket;
In the cooling structure of the electric motor, on the inner surface of the end bracket, a brush for supplying power by sliding contact with a commutator provided in the armature is disposed.
While forming a first ventilation hole in the end portion constituting the bottom surface of the yoke,
A cooling structure for an electric motor, wherein a second ventilation hole is formed in the vicinity of the brush of the end bracket.   2. The cooling structure for an electric motor according to claim 1, wherein a recess for housing the brush is formed on an inner surface of the end bracket, and the second ventilation hole is formed on a peripheral surface of the recess. The end bracket is provided with a plurality of stays for fixing to an external device,
The cooling structure for an electric motor according to claim 1 or 2, wherein the plurality of stays are arranged at positions where the second ventilation holes are avoided in the circumferential direction.

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