JP5009220B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor for driving a cooling fan in which a fan blade is fixed to an outer rotor, for example.

  Conventionally, an outer rotor type electric brushless motor is sometimes used as a fan motor for cooling a radiator of an automobile. This type of electric motor forms a stator by winding a coil around a plurality of teeth provided on a stator base, and has a bottomed cylindrical rotor yoke that covers the teeth and a permanent magnet disposed on the inner peripheral surface of the rotor yoke. And a rotor, and the rotation shaft of the rotor yoke is rotatably supported on the stator base. Fan blades are provided on the outer peripheral wall of the rotor yoke, and when a current is supplied to the coil, a magnetic field is formed on the stator teeth, and a magnetic attraction and repulsive force is generated between the rotor yoke and the permanent magnets. The cooling air is generated in the axial direction of the rotation shaft by rotating and fan blades.

In this type of electric motor, since the rotor as a rotor rotates outside the stator as a stator, if an attempt is made to ensure watertightness inside, a separate cover is required and the size is increased. For this reason, in many cases, the rotor yoke is usually an open type in which the rotor yoke is exposed, and as a result, water tends to easily enter from the outside.
For example, in the device described in Patent Document 1, a waterproof wall is provided to prevent water from entering from the air intake port on the front surface of the rotor yoke provided for cooling the inside. It has the structure which provided the drain hole for discharging | emitting to the exterior (for example, refer patent document 1).
JP 2004-40934 A

  However, in the above-described prior art, when the electric motor is stopped, the drain hole may not be positioned vertically downward depending on the stop angle of the rotor yoke. In such a case, the water that has entered the interior when the electric motor is stopped is not completely drained and remains in the interior. That is, there is a problem that the amount of drained water varies depending on the stop angle of the rotor yoke.

  In addition, since the drain hole is not formed in the outermost periphery of the rotor yoke, depending on the installation angle of the electric motor, even if the drain hole is positioned vertically downward when the motor is stopped, a water pool portion is formed. Therefore, it is difficult to reliably drain water. If the remaining water is left as it is, there is a possibility that the water may freeze, for example, when used in a cold region, and this causes a problem that the electric motor is locked.

  Therefore, the present invention has been made in view of the above-described circumstances, and provides an electric motor that can drain water reliably and prevent freeze lock regardless of the stop angle of the rotor yoke. Is.

In order to solve the above problems, the invention described in claim 1 is a stator having a plurality of teeth for winding a coil and a slot formed between the teeth, and is rotatable with respect to the stator. An electric motor having a bottomed cylindrical rotor yoke that covers the stator from its front surface and a permanent magnet disposed on an inner peripheral surface of the rotor yoke. A plurality of drain holes are formed along the circumferential direction for draining water that has entered the interior to the outside at a connection portion between the bottom wall and the peripheral wall of the rotor yoke, and in the vicinity thereof, and forming the drain holes The number is set to a common multiple of the number of slots and the number of magnetic poles.
By comprising in this way, a water reservoir part is hard to be formed and it becomes possible to drain the water inside a motor efficiently. In addition, since the number of drain holes formed is set to a common multiple of the number of slots and the number of permanent magnets, the drain holes can be positioned at the bottom without depending on the stop angle of the rotor yoke when the electric motor is stopped. Become.

The invention described in claim 2 is characterized in that the number of drain holes formed is set to the least common multiple of the number of slots and the number of magnetic poles.
In this way, by setting the number of drain holes to be the least common multiple of the number of slots and the number of magnetic poles, the drain holes are positioned at the bottom corresponding to the stop position of each rotor yoke, and the rotor yoke Stiffness can be maintained.

According to a third aspect of the present invention, when the rotor is installed so that the bottom wall is along the vertical direction, the drain hole of the rotor is at the lowest position at a position where the rotor is stopped by cogging torque when no power is supplied. It is characterized by being formed.
Here, in the electric motor, cogging torque is generated in the rotor yoke in a non-energized state by the magnetic force of the permanent magnet disposed in the rotor yoke. For this reason, the stop angle of the rotor yoke is determined by the arrangement position of the permanent magnet and the number of magnetic poles.
Therefore, as in the invention described in claim 3, in addition to setting the number of drain holes formed to the common multiple of the number of slots and the number of permanent magnets, or the least common multiple, the drain holes are provided when the rotor is not energized. By forming at the lowermost position at the position stopped by the cogging torque, it becomes possible to drain the water inside the electric motor more reliably.

The invention described in claim 4 comprises a stator having a plurality of teeth for winding a coil and a slot formed between the teeth, and a rotor provided rotatably with respect to the stator, The rotor is an electric motor having a bottomed cylindrical rotor yoke that covers the stator from the front surface thereof, and a permanent magnet disposed on an inner peripheral surface of the rotor yoke, and includes a bottom wall and a peripheral wall of the rotor yoke. A plurality of drain holes for draining water that has entered the interior to the outside are formed along the circumferential direction, and the rotor is installed so that the bottom wall is along the vertical direction. The drain hole of the rotor is formed at a lowermost portion at a position where the rotor is stopped by cogging torque when the rotor is not energized.
In this way, the water drainage hole is formed in the lowermost part at the position where the rotor is stopped by the cogging torque when no power is supplied, so that the water inside the motor can be drained efficiently without forming a water pool portion. Become.

According to the first aspect of the present invention, it is difficult to form a water pool portion, and water inside the motor can be efficiently drained. In addition, since the number of drain holes formed is set to the least common multiple of the number of slots and the number of permanent magnets, the drain holes can be positioned at the bottom without depending on the stop angle of the rotor yoke when the electric motor is stopped. become.
For this reason, since the water which entered the inside can be drained reliably, it is possible to prevent the electric motor from being locked due to water freezing due to use in a cold region.

  According to the second aspect of the present invention, by setting the number of drain holes to be the least common multiple of the number of slots and the number of magnetic poles, the drain holes are formed at the bottom corresponding to the stop position of each rotor yoke. Thus, the rigidity of the rotor yoke can be maintained. For this reason, damage to the rotor yoke can be prevented, and a highly safe electric motor can be provided.

  According to the invention described in claim 3, in addition to setting the number of drain holes formed to the common multiple of the number of slots and the number of permanent magnets, or the least common multiple, the water drain hole has a cogging torque when the rotor is not energized. It becomes possible to drain the water inside the electric motor more reliably by forming it at the lowermost position at the position where it stops.

  According to the fourth aspect of the present invention, the water drainage hole is formed in the lowermost portion at the position where the rotor is stopped by the cogging torque when the rotor is not energized, so that the water inside the motor can be efficiently formed without forming the water pool portion. It becomes possible to drain the water. For this reason, since the water which permeated inside can be drained reliably, it can prevent more reliably that water freezes by use in a cold region and an electric motor locks.

Next, embodiments of the present invention will be described with reference to the drawings. In the following description, the left side of FIG. 1 is the front side, and the right side of FIG. 1 is the rear side.
1 to 3, reference numeral 1 denotes a fan motor. The fan motor 1 is for cooling an automobile radiator. The fan motor 1 includes a brushless type electric motor M and a fan blade 3 supported by a rotor R of the electric motor M. The rotor R is an outer rotor type, and a stator S is provided in the rotor R. By attaching the stator base 4 of the stator S to the radiator, the electric motor M is in a state in which the rotating shaft 6 of the rotor R is arranged along the horizontal direction (front-rear direction).

  The stator base 4 is made of aluminum and is provided with three mounting pieces 5 attached to the radiator. In the central portion of the rear surface of the stator base 4, a housing portion 9 for the sensor unit 8 is formed around the rotating shaft 6 of the rotor R and surrounded by the vertical wall 7. The housing portion 9 has four screws. 10 is closed by the lid 2.

A boss portion 11 is provided at the center of the front surface of the stator base 4. A step portion 12 is formed around the boss portion 11. A stator core 14 is disposed at the stepped portion 12, and is attached to the boss portion 11 from the axial direction of the rotating shaft 6 by three fixing bolts 15.
The stator core 14 is formed by laminating metal plates made of a magnetic material in the axial direction of the rotary shaft 6, and includes twelve teeth 13 for winding the coils 17 in the radial direction. Twelve dovetail-shaped slots 13a that are elongated in the axial direction are formed between the teeth 13. The coil 17 is wound around the tooth 13 through the slot 13a.

  Each tooth 13 is preinstalled with an insulator 16 having a U-shaped cross section, which is an insulating material, and a coil 17 is wound around the tooth 13 via the insulator 16. Further, the stator S is provided such that the center P of an arbitrary pair of teeth 13 that are opposed to each other around the rotating shaft 6 among the 12 teeth 13 of the stator core 14 is along the vertical direction (FIG. 2). reference).

  Here, on the inner wall 18 of each insulator 16, ring-shaped insulator rings 19 and 20 that rise in the axial direction of the rotary shaft 6 along the inner wall 18 are locked to the root portion of the insulator 16. A pair of front and rear sides of S are mounted. At the lower part of each insulator ring 19, 20, a cutout portion 37 is provided for reducing the height within an angle range of 90 degrees in order to enhance drainage (see FIG. 2). The stator S is composed of the stator base 4 and the stator core 14 around which the coil 17 is wound.

A recess 21 is formed around the boss portion 11 on the front surface of the stator base 4, and an annular terminal unit 22 is supported by the recess 21. The terminal unit 22 is connected to the coils 17 corresponding to the U-phase, V-phase, and W-phase, and is fixed in a state where the U-phase, V-phase, and W-phase terminals 24 are pressed by a double nut 23. Here, the recess 21 is filled with the resin material J having excellent heat transferability around the terminal unit 22 and the terminal 24, and the heat generated in the coil 17 is effectively applied to the stator base 4 via the resin material J. Heated and quickly cooled.
As shown in FIG. 4, a cable 25 is connected to each terminal 24, and the terminal 24 and the cable 25 are covered with a waterproof tube 26.

A mounting hole 28 for the bearing holder 27 is formed at the center of the boss portion 11 of the stator base 4, and the bearing holder 27 is inserted therein.
As shown in FIGS. 5 and 6, the bearing holder 27 is an iron-made cylindrical member, and the first bearing 29 and the second bearing 30 are fitted and fixed to the front end portion and the rear end portion, respectively. The part 31 and the second holding part 32 are stepped. Thus, by forming the bearing holder 27 with an iron member equivalent to the first bearing 29 and the second bearing 30, the degree of expansion and contraction due to relative heat between the bearing holder 27 and the first and second bearings 29 and 30. Are equivalent.
Therefore, the change of the internal gap based on the expansion and contraction due to the heat of the first bearing 29 and the second bearing 30 can be greatly reduced, the sound vibration performance of the first bearing 29 and the second bearing 30 can be improved and the life can be extended. .

  Three flange portions 33 are formed around the neck portion of the first holding portion 31 of the bearing holder 27, and the flange portions 33 are fixed to the boss portion 11 of the stator base 4 by screws 34. Further, a water shield ring portion 35 extending outward is formed on the periphery of the front end portion of the first holding portion 31, and the water shield ring portion 35 is a cut portion in which a lower portion is cut in an angle range of 90 degrees in order to improve drainage. 38. An insertion hole 36 for loosely inserting the rotating shaft 6 is formed on the first holding portion 31 side at the center portion of the bearing holder 27.

  A reduced diameter portion 40 is formed on the outer peripheral portion of the bearing holder 27 over the entire circumference, and an annular gap portion 41 is formed between the mounting hole 28 of the boss portion 11 and the reduced diameter portion. A communication hole 42 communicating with the inside of the bearing holder 27 is formed in the lower portion of 40. The reduced diameter portion 40 is formed in the storage portion 9 of the sensor unit 8 located on the rear end side of the mounting hole 28 of the boss portion 11 through the communication grooves 43 formed at three locations in the circumferential direction on the rear end portion of the bearing holder 27. Communicate.

As shown in FIG. 1, a communication hole 44 is formed in a lower portion of the boss portion 11 of the stator base 4 at a position communicating with the gap portion 41 toward the lower portion, and this communication hole 44 is an outer peripheral wall of the boss portion 11. The terminal unit 22 is opened to the arrangement site.
The mounting hole 28 of the boss portion 11 is formed as a storage portion 9 of the sensor unit 8 at a portion rearward of the rear end portion of the bearing holder 27. A disc-shaped sensor magnet 47 that is fixed to the rear end screw portion 45 of the rotating shaft 6 by a nut 46 and rotates together with the rotating shaft 6 is accommodated in the accommodating portion 9. As shown in FIG. 4, a fan-shaped sensor case 49 is fixed to the screw hole 48 of the stator base 4 with a screw 50 corresponding to the sensor magnet 47. The sensor magnet 47 and the sensor case 49 constitute a sensor unit 8.

  The sensor case 49 is a member in which a circuit component 56 is accommodated. As shown in FIG. A pair of attachment pieces 51 are formed which are tightened by (see FIGS. 3 and 4). A long mounting hole 52 for positioning is provided in the mounting piece 51 so that the sensor case 49 can be moved along the rotational peripheral surface of the sensor magnet 47.

  As shown in FIGS. 1 and 3, a rib portion 53 extending in the radial direction from the vertical wall 7 of the storage portion 9 is provided in the lower portion of the stator base 4, and a drainage passage 54 is formed in the rib portion 53. . The upper end of the drainage passage 54 communicates with the storage portion 9, the lower end of the drainage passage 54 is not opened linearly, is closed with screws, and the opening end 55 is bent forward and opened at the front surface of the stator base 4. A harness 57 is connected to the circuit component 56 in the sensor case 49.

  8 and 9, R represents a rotor. The rotor R mainly corresponds to the coil 17 of the stator S on the inner surface of the bottomed cylindrical rotor yoke 60 that covers the stator S from the front surface and the peripheral wall 61 of the rotor yoke 60. It is composed of eight magnets 62 arranged. That is, the rotor yoke 60 is in a state in which the bottom wall 63 is along the vertical direction (vertical direction in FIG. 1).

  A boss 64 protruding forward is formed at the center of the bottom wall 63 of the rotor yoke 60, and the rotating shaft 6 is inserted into the boss 64. The distal end portion of the rotating shaft 6 protrudes from the end face of the boss 64, and this protruding portion is a screw portion 65, and a nut 66 is tightened here to fix the rotating shaft 6 to the boss 64 of the rotor yoke 60. The rotary shaft 6 is formed with a flange portion 67 that contacts the bottom wall 63 of the rotor yoke 60 from the back side, and the first bearing 29 is press-fitted and fixed from the front end side of the rotary shaft 6 so as to contact the flange portion 67.

Twenty-four substantially circular drain holes 68 are formed at equal intervals in the circumferential direction at the connection portion between the bottom wall 63 and the peripheral wall 61 of the rotor yoke 60. The drain hole 68 is for draining the water that has entered the electric motor M to the outside.
Here, the number of drain holes 68 formed is set to the least common multiple of the number of slots 13a formed in the stator core 14 and the number of magnets 62, that is, the number of magnetic poles. That is, in this embodiment, 12 slots 13a are formed and 8 magnets 62 are provided, that is, 8 magnetic poles are provided. Therefore, the least common multiple of “12” and “8” is “24”. It becomes. For this reason, in the drain holes 68, 24 drain holes 68 are formed at equal intervals along the circumferential direction at the connecting portion between the bottom wall 63 and the peripheral wall 61 of the rotor yoke 60. 24 pieces are formed on the bottom wall 63.

In more detail, based on FIGS. 10-11, the formation position of these 24 drain holes 68 is demonstrated.
FIG. 10 is an explanatory view showing the positional relationship between the magnet 62 and the drain hole 68. As shown in the figure, the drain holes 68 are formed between the respective magnets 62, that is, between the drain holes 68a formed at portions corresponding to the respective magnetic poles, and between the drain holes 68a. It is comprised with the hole 68b. The formation positions of the drain holes 68a and 68b correspond to the lowermost portion of the rotor yoke 60 at the stop position when the electric motor M is in a non-energized state, that is, when the coil 17 is not excited.

This will be described with reference to FIG. The figure is an explanatory view showing the behavior of the rotor R with respect to the stator S of the electric motor M.
When the rotor R rotates counterclockwise, it is driven so as to reach from FIG. 11A to FIG. When the rotor R is in the state shown in FIG. 11 (b), FIG. 11 (d), FIG. 11 (f), and FIG. 11 (h) shown in the lower stage, the rotor yoke 60 has one of the boundary lines P ′ of the plurality of magnetic poles. It is in the state located in the slot 13a. In such a case, the magnetic attraction force by the magnet 62 is balanced in the circumferential direction. Here, the stop angle of the rotor R is determined by the location where the cogging torque is generated. That is, when the electric motor M is in a non-energized state, the cogging torque repeats a stable state in which the magnetic attraction force by the magnet 62 of the rotor R is balanced in the circumferential direction and an unstable state in which the balance is not balanced. Torque unevenness caused by what happens. For this reason, the rotor R stops at the position of the stable state by the cogging torque generated when moving from the stable state to the unstable state.

  Therefore, when the electric motor M is in a non-energized state, the rotor R is not connected to any of the magnetic pole boundary lines P ′ as shown in FIGS. 11 (b), 11 (d), 11 (f), and 11 (h). Stops when it is located in the slot 13a. For this reason, the drain holes 68 (68a, 68b) are formed in the lowermost part (two-dot chain line in FIG. 11) of the bottom wall 63 of the rotor yoke 60 when the rotor yoke 60 can be stopped.

  Further, as is clear from FIGS. 11B, 11D, 11F, and 11H, the location where the cogging torque is generated is determined by the number of slots 13a and the number of magnetic poles. There are only the least common multiple. For this reason, by setting the number of drain holes 68 to the least common multiple of the number of slots 13a and the number of magnetic poles, the drain holes 68 can be reliably secured when the electric motor M is stopped regardless of the stop angle of the rotor yoke 60. Can be positioned at the bottom of the rotor yoke 60.

  As shown in FIG. 8, the peripheral wall 61 of the rotor yoke 60 is formed thicker than the bottom wall 63, and a magnet cover 69 is press-fitted and fixed to the inner surface of the peripheral wall 61. The opening edge 70 of the peripheral wall 61 of the rotor yoke 60 is disposed so as to face the front surface of the stator base 4 and extends to a position close to form a gap 71 between the front surface of the stator base 4 (see FIG. 1).

  As shown in FIGS. 12 and 13, the magnet cover 69 is formed by forming a plate material into a cylindrical shape, and the opening edge of the rear portion is expanded to form a diameter-expanded portion 72. The diameter-expanded portion 72 is formed on the rotor yoke 60. It is press-fitted and fixed to the inner surface of the peripheral wall 61. An inner flange portion 73 directed inward is formed at the opening edge of the front portion. A peripheral wall 74 extending from the enlarged diameter portion 72 to the inner flange portion 73 has a slightly smaller diameter than the inner surface of the peripheral wall 61 of the rotor yoke 60, and an accommodating portion 75 is formed between the peripheral wall 74 and the inner surface of the peripheral wall 61 of the rotor yoke 60. The magnets 62 are attached to the housing portion 75 at eight locations partitioned by the magnet holder 76 (see FIGS. 1 and 8).

  In the magnet cover 69, a plurality of drain holes 59 are formed in the circumferential direction at the ridge line portion between the inner flange portion 73 and the peripheral wall 74. Here, the drain hole 59 of the magnet cover 69 is located slightly inward in the radial direction with respect to the drain hole 68 of the rotor yoke 60, and the drain hole 68 of the rotor yoke 60 is positioned rearward in the axial direction of the rotating shaft 6. It can be effectively used as an inlet for the filler Z to be filled into the magnet 62.

As shown in FIGS. 1, 8, and 9, three attachment holes 77 are formed around the boss 64 of the bottom wall 63 of the rotor yoke 60, and the water shield ring 80 is formed in the attachment hole 77 from the back surface of the bottom wall 63. Rivet 81 is fixed.
As shown in FIG. 14, the water shield ring 80 is an annular member composed of an inner ring portion 82, an outer ring portion 83, and a bottom portion 84, and the outer ring portion 83 is raised so that the diameter increases toward the outer side. The inner ring portion 82 is formed so as to rise along the axial direction of the rotary shaft 6. The peripheral portion of the outer ring portion 83 is inside the peripheral wall of the insulator ring 19 and close to the midway portion in the height direction, and the inner ring portion 82 is close to the outside of the water shield ring portion 35 of the bearing holder 27, and the water shield ring It stands up to a position that blocks the periphery of the portion 35.

  Therefore, a labyrinth portion 98 which is a meandering and long path is formed between the outer ring portion 83 of the water shield ring 80 and the peripheral wall of the insulator ring 19 in order to ensure the length of the water intrusion path, and the water shield Between the inner ring portion 82 of the ring 80 and the water shield ring portion 35 of the bearing holder 27, a labyrinth portion 99 that is a meandering long path is formed in order to ensure the length of the water intrusion route. Become.

  As shown in FIG. 1, a resin fan boss 86 is attached to the front surface of the bottom wall 63 of the rotor yoke 60 via six screws 85. The fan boss 86 includes a shoulder portion 87 that rises around the boss 64 of the bottom wall 63 of the rotor yoke 60, a bottom wall portion 88 that covers the bottom wall 63 of the rotor yoke 60, and a peripheral wall portion 89 that covers the peripheral wall 61 of the rotor yoke 60 to the middle portion. The fan blade 3 is integrally formed on the peripheral wall portion 89. Here, the outer peripheral portion of the bottom wall portion 88 of the fan boss 86 is formed in a stepped manner so as to be separated from the bottom wall 63 of the rotor yoke 60, so as not to close the drain hole 68 of the rotor yoke 60.

In the vicinity of the opening edge of the peripheral wall portion 89 of the fan boss 86, an annular waterproof ring 90 having a U-shaped cross section is fixed to the fan shroud 91 provided on the mounting piece 5, and the opening edge 70 of the peripheral wall 61 of the rotor yoke 60 is The gap 71 formed between the stator base 4 and the front surface of the stator base 4 is disposed so as to cover from the outside.
Therefore, a narrow gap 97 is formed between the opening edge of the fan boss 86 and the front flange portion 90 a of the waterproof ring 90.

  The front surface of the stator base 4 is close to the inner surface of the peripheral wall 61 of the rotor yoke 60, extends in front of the opening edge 70 of the rotor yoke 60 in the axial direction of the rotary shaft 6, and extends in the direction along the axial direction of the peripheral wall 61 and the rotary shaft 6. A ring portion 92 is formed so as to be overlapped. An end edge of the ring portion 92 extends to the front side of the rear end portion of the coil 17, and a protrusion 93 is provided at the terminal portion toward the inner surface of the peripheral wall 61 of the rotor yoke 60. Here, as shown in FIG. 2, the ridge 93 is cut off at an angle range of 90 degrees (see FIG. 2). 100.

Therefore, between the opening edge 70 of the rotor yoke 60 and the front surface of the stator base 4, in order to ensure the length of the water intrusion path, the gap between the opening edge 70 of the peripheral wall 61 of the rotor yoke 60 and the front surface of the stator base 4. A labyrinth portion 94 communicating with the gap 71 is formed.
Here, the labyrinth portion 94 wraps further outward from between the ring portion 92 and the inner surface of the peripheral wall 61 of the rotor yoke 60 by the protrusion 93, meanderingly and has a long path.

  Therefore, according to the above-described embodiment, since the plurality of drain holes 68 are formed in the connection portion between the bottom wall 63 and the peripheral wall 61 of the rotor yoke 60, water is provided near the connection portion between the bottom wall 63 and the peripheral wall 61. The reservoir portion W (see FIG. 1) is not easily formed, and the water that has entered the electric motor M can be reliably and quickly drained. For this reason, since the water which permeated the inside can be drained reliably, it is possible to prevent the electric motor M from being locked due to freezing of water due to use in a cold region.

  Further, since the number of drain holes 68 formed in the rotor yoke 60 is set to “24” which is the least common multiple of the number “12” of the slots 13a and the number of installed magnets 62 (the number of magnetic poles) “8”. When the electric motor M is stopped, the drain hole 68 can be positioned below the rotor yoke 60 without depending on the stop angle of the rotor yoke 60.

  In addition, the drain holes 68 are constituted by drain holes 68a formed at portions corresponding to the respective magnetic poles, and drain holes 68b formed between the drain holes 68a. For this reason, when the electric motor M is in a non-energized state, that is, when the coil 17 is not excited, the drain hole 68 can be reliably positioned at the lowermost portion of the rotor yoke 60 at the stop position. Therefore, it becomes possible to drain the water inside the electric motor M more reliably and quickly.

Furthermore, since the drain hole 59 of the magnet cover 69 is formed at a portion corresponding to the drain hole 68 of the rotor yoke 60, the drainage function of the water submerged in the rotor R is not impaired, and the electric motor by submersion is not damaged. It becomes possible to prevent the failure of M.
In particular, as in this embodiment, when the rotor R is an outer rotor type, if it is intended to ensure the watertightness inside the electric motor M, a separate cover is required and the size is increased. For this reason, it is usually an open type in which the rotor yoke 60 is exposed, and it is difficult to ensure water tightness inside the electric motor M. However, according to this embodiment, it becomes possible to drain the water inside the electric motor M effectively.

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 case where 24 drain holes 68 are formed in the rotor yoke 60 has been described. However, the present invention is not limited to this, and the number of slots 13a (teeth 13) of the stator core 14 is not limited thereto. The number of drain holes 68 is determined by the number of magnetic poles.

Furthermore, in the above-described embodiment, the stator S is provided such that the center P of any pair of teeth 13 that are opposed to each other around the rotation shaft 6 out of the 12 teeth 13 of the stator core 14 is along the vertical direction. Explained the case. However, the present invention is not limited to this, and the stator S may be provided so that the center P of any pair of teeth 13 intersects the vertical direction. In this case, the stop position of the rotor yoke 60 when the electric motor M is not energized, that is, the stop position of the magnet 62 is also shifted in the circumferential direction based on the tilt angle of the center P of the teeth 13. For this reason, it is desirable to shift the formation position of the drain hole 68 of the rotor yoke 60 in the circumferential direction accordingly, and to reliably form the drain hole 68 at the lowermost part of the bottom wall 63 at the stop position of the rotor yoke 60.
In the above-described embodiment, the case where 24 drain holes 68 are formed in the connection portion between the bottom wall 63 and the peripheral wall 61 of the rotor yoke 60 has been described. However, it may be in the vicinity of the connecting portion, and the drain hole 68 may be formed only in the bottom wall 63 and the peripheral wall 61.

  Moreover, in the above-mentioned embodiment, the stator P of the fan motor 1 is provided so that the center P of an arbitrary pair of teeth 13 that are opposed to each other about the rotation shaft 6 is along the vertical direction. A case has been described in which the drainage holes 68a are formed between the magnets 62, that is, between the magnetic poles, and the drainage holes 68b are formed between the drainage holes 68a. However, in the case where the stator S of the fan motor 1 is arranged so that the center of the slot 13a formed between the adjacent teeth 13 is located directly below, the position of the drain hole 68 is the same as the center P of the tooth 13. The angular difference from the center of the slot 13a is shifted in the circumferential direction. That is, the position at which the cogging torque is generated is determined by the positional relationship between the teeth 13 and the magnets 62. Therefore, if the fixing angle of the teeth 13 is changed, the lowermost portion of the rotor yoke 60 naturally when the electric motor M is stopped. The position of also changes. Therefore, in this embodiment, when the stator S is fixed so that the center of the slot 13a is located directly below, all three drain holes 68 are formed at locations corresponding to the magnetic poles.

  Further, in the above-described embodiment, the number of drain holes 68 formed in the rotor yoke 60 is “24” which is the least common multiple of the number “12” of the slots 13 a and the number of installed magnets 62 (the number of magnetic poles) “8”. The case where it is set has been described. However, the present invention is not limited to this, and the number of drain holes 68 formed in the rotor yoke 60 may be a common multiple of the number of slots 13a and the number of installed magnets 62. Further, cogging may be performed when the rotor yoke 60 is not energized. If the drain holes 68 are formed at the lowest position of the stopped rotor yoke 60 at the position where the torque is stopped by the torque, the number of the drain holes 68 need not be limited. Note that if the number of drain holes 68 formed in the rotor yoke 60 is the least common multiple of the number of slots 13a and the number of magnets 62 installed, the number of drain holes 68 formed is smaller than when the installed number is a common multiple. Therefore, the rigidity of the rotor yoke 60 can be maintained.

  And in the above-mentioned embodiment, the case where the substantially circular water drain hole 68 was formed in the connection part of the bottom wall 63 of the rotor yoke 60 and the surrounding wall 61 at equal intervals along the circumferential direction was demonstrated. However, the drain hole 68 is not limited to a circular shape, and may be, for example, a long hole shape or a substantially gourd shape in plan view in which two holes partially overlap.

It is sectional drawing of the fan motor of embodiment of this invention. It is a front view of the stator of FIG. It is a rear view of FIG. 2 which abbreviate | omitted the sensor unit. It is a rear view of FIG. It is an expanded sectional view of the bearing holder of FIG. FIG. 6 is a front view of FIG. 5. It is a front view of a sensor case. It is sectional drawing of the rotor of FIG. It is a front view of FIG. It is explanatory drawing which shows the positional relationship of a neodymium magnet and a drain hole. It is explanatory drawing which shows the behavior of a rotor. It is a side view of the magnet cover of FIG. It is a front view of FIG. It is a side view of a magnet holder.

Explanation of symbols

1 fan motor 13 teeth 13a slot 17 coil 60 rotor yoke 61 peripheral wall 62 neodymium magnet (permanent magnet)
63 Bottom wall 68, 68a, 68b Drain hole M Electric motor P Center P 'Boundary line R Rotor S Stator

Claims (4)

A stator having a plurality of teeth for winding a coil and a slot formed between the teeth;
A rotor provided rotatably with respect to the stator,
The rotor is
An electric motor having a bottomed cylindrical rotor yoke that covers the stator from the front surface thereof and a permanent magnet disposed on the inner peripheral surface of the rotor yoke,
A plurality of drain holes are formed along the circumferential direction for draining water that has entered the outside to the outside at the connection portion between the bottom wall and the peripheral wall of the rotor yoke, and in the vicinity thereof.
An electric motor characterized in that the number of drain holes formed is set to a common multiple of the number of slots and the number of magnetic poles.   The electric motor according to claim 1, wherein the number of drain holes formed is set to the least common multiple of the number of slots and the number of magnetic poles. When the rotor is installed so that the bottom wall is along the vertical direction,
3. The electric motor according to claim 1, wherein the drain hole of the rotor is formed at a lowermost portion at a position where the rotor is stopped by a cogging torque when the rotor is not energized. A stator having a plurality of teeth for winding a coil and a slot formed between the teeth;
A rotor provided rotatably with respect to the stator,
The rotor is
An electric motor having a bottomed cylindrical rotor yoke that covers the stator from the front surface thereof and a permanent magnet disposed on the inner peripheral surface of the rotor yoke,
A plurality of drain holes are formed along the circumferential direction for draining water that has entered the outside to the outside at the connection portion between the bottom wall and the peripheral wall of the rotor yoke, and in the vicinity thereof.
When the rotor is installed so that the bottom wall is along the vertical direction,
The electric motor according to claim 1, wherein the drain hole of the rotor is formed at a lowermost portion at a position where the rotor is stopped by a cogging torque when no power is supplied.

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