JP2017028979A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor capable of suppressing the wetting of bearings, while ensuring the cooling performance in the motor.SOLUTION: A coupling part 38 for coupling an outer cylinder 34 and an inner cylinder 36 is formed in a rotor housing 18, and a ventilation hole 48 penetrating the inner cylinder 36 in the axial direction is formed in the coupling part 38. A circular groove 24 extending in the circumferential direction of a support 20, and opening to one side thereof in the axial direction is formed in a center piece 16. The inner cylinder 36 extends from one side of the support 20 in the axial direction toward the support 20, and the tip 44 of the inner cylinder 36 is inserted into the groove 24, and constitutes a labyrinth structure 46 in conjunction with the groove 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brushless motor.

  Conventionally, a rotor housing having a shaft, an annular stator core provided coaxially with the shaft, an outer cylindrical portion disposed radially outside the stator core, and an inner cylindrical portion supported by the shaft via a bearing, There is a brushless motor including a center piece that supports a shaft and holds a stator core (see, for example, Patent Document 1).

Japanese Patent No. 5064992

  In such a brushless motor, a ventilation hole may be formed in the rotor housing in order to ensure the cooling performance inside the motor. However, if a ventilation hole is formed in the rotor housing, there is a risk that the bearing will be wet if water droplets enter through the ventilation hole.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a brushless motor capable of suppressing the wetness of the bearing while ensuring the cooling performance inside the motor.

  In order to solve the above problems, a brushless motor according to claim 1 is provided with a shaft, an annular stator core provided coaxially with the shaft, and provided annularly around the shaft. And a groove that is formed in a circular shape in the support portion along the circumferential direction of the support portion and that opens to one axial side of the support portion. A center piece, an outer cylindrical portion disposed on the radially outer side of the stator core and having a rotor magnet fixed to an inner peripheral surface thereof, supported by the shaft via a bearing, and axially directed to the support portion An inner cylinder portion extending from one side toward the support portion and having a tip portion inserted inside the groove to form a labyrinth structure with the groove; and the outer cylinder portion and the inner portion While connecting the ends of one side in the axial direction of the parts, and a rotor housing having a connecting portion for ventilation hole is formed penetrating along the axial direction of the inner cylinder part.

  According to this brushless motor, the rotor housing is formed with a connecting portion that connects the outer cylinder portion and the inner cylinder portion, and the connecting portion has a ventilation hole penetrating along the axial direction of the inner cylinder portion. Is formed. Therefore, since the cooling air can be taken into the motor through this ventilation hole, the cooling performance inside the motor can be ensured.

  Further, the inner cylinder portion extends from the one side in the axial direction with respect to the support portion toward the support portion, and the distal end portion of the inner cylinder portion is inserted inside the groove formed in the support portion of the center piece, The groove forms a labyrinth structure. Therefore, even if water drops that have entered the motor through the ventilation holes flow to the support part side along the outer peripheral surface of the inner cylinder part, the water drops can enter the inner cylinder part from the tip side of the inner cylinder part. It can be prevented by the labyrinth structure. Thereby, the moisture of a bearing can be suppressed.

  The brushless motor according to claim 2 is the brushless motor according to claim 1, wherein the support portion extends along the axial direction of the support portion, and one side in the axial direction opens to the bottom surface of the groove. A communication hole is formed in which the other side opens on the end surface on the other axial side of the support portion.

  According to this brushless motor, the support portion is formed with a communication hole extending along the axial direction of the support portion, and one side in the axial direction of the communication hole opens to the bottom surface of the groove, and the shaft of the communication hole is formed. The other side in the direction opens to the end surface on the other side in the axial direction of the support portion. Therefore, even if water droplets that are prevented from entering the inner cylinder portion by the labyrinth structure accumulate in the groove, the water droplets can be discharged to the outside through the communication hole. Thereby, the moisture of a bearing can be suppressed much more effectively.

  A brushless motor according to a third aspect is the brushless motor according to the second aspect, further comprising a cover that closes an opening on one axial side of the inner cylindrical portion.

  According to this brushless motor, the opening on the one side in the axial direction of the inner cylinder part is closed by the cover, so that water droplets enter the inside of the inner cylinder part from the opening on the one side in the axial direction of the inner cylinder part, The cover can prevent the bearing from being directly exposed to water.

  A brushless motor according to a fourth aspect of the invention is the brushless motor according to the third aspect, comprising a first cover as the cover and a second cover that closes an opening on the other axial side of the communication hole, The center piece is formed in an annular shape around the support portion, and has an annular portion facing the opening on the other axial side of the rotor housing, and the annular portion is provided along the axial direction of the support portion. A through-hole that penetrates is formed.

  According to this brushless motor, a through-hole penetrating along the axial direction of the support portion is formed in the annular portion of the center piece. Therefore, for example, even when the brushless motor is arranged upside down, the cooling air is taken into the motor through the through hole formed in the annular portion, and the cooling air taken into the motor passes through the ventilation hole. Since it is discharged to the outside of the motor, the cooling performance inside the motor can be secured.

  If the brushless motor is placed upside down, water droplets may enter the motor through this through-hole. However, as described above, the tip of the inner cylinder and the groove constitute a labyrinth structure. Therefore, the labyrinth structure can prevent the water droplets from entering the inner cylinder portion and the bearing from getting wet.

  Also, since the opening on the other axial side of the communication hole is closed by the second cover, even when the brushless motor is arranged upside down, water droplets can enter from the opening on the other axial side of the communication hole. It is possible to suppress the bearing from being directly wetted by the second or bar.

  The brushless motor according to claim 5 is the brushless motor according to any one of claims 1 to 4, wherein an axial central portion of the rotor magnet is in an axial central portion of the stator core. Is shifted to one side in the axial direction.

  For example, when a fan is attached to the rotor housing and the fan rotates together with the rotor composed of the rotor housing and the rotor magnet, buoyancy (payload force) is generated in one axial direction with respect to the rotating portion composed of the rotor and the fan. There is a risk of doing. As described above, when buoyancy is generated on one side in the axial direction with respect to the rotating portion, a force on one side in the axial direction acts on the bearing, and the rotor may move together with the bearing toward one side in the axial direction. is there.

  In this regard, according to the brushless motor of the fifth aspect, the central portion of the rotor magnet in the axial direction is shifted to one axial side with respect to the central portion of the stator core in the axial direction. Therefore, since the attractive force acts on the other side in the axial direction from the stator core to the rotor magnet, that is, on the side opposite to the above buoyancy, the rotor can be prevented from moving to the one side in the axial direction.

  Thereby, it is possible to avoid the rotor from coming off and improve the reliability, and also to maintain the labyrinth structure and improve the waterproofing reliability of the bearing. Furthermore, the thrust load acting on the bearing can be reduced, the life of the bearing can be improved, and the size of the press-fitting margin between the bearing and the shaft can be reduced.

It is a longitudinal cross-sectional view of the brushless motor which concerns on one Embodiment of this invention. It is a figure which shows the 1st modification of the brushless motor shown by FIG. It is a figure which shows the state which the buoyancy (payload force) to the axial direction one side has generate | occur | produced with respect to the rotation part which consists of a rotor and a fan in the brushless motor shown by FIG. It is a figure which shows the 2nd modification of the brushless motor shown by FIG.

  Hereinafter, an embodiment of the present invention will be described.

  As shown in FIG. 1, the brushless motor 10 according to an embodiment of the present invention includes a shaft 12, a stator core 14, a center piece 16, and a rotor housing 18.

  In FIG. 1, an arrow A1 indicates one axial direction of each member, and an arrow A2 indicates the other axial direction of each member.

  The stator core 14 is formed in an annular shape and is provided coaxially with the shaft 12. In FIG. 1, the stator core 14 is illustrated in a simplified manner. More specifically, the stator core 14 is formed with a plurality of teeth extending radially about the shaft 12. The winding is wound. The stator core 14 and the winding constitute a stator 15 that generates a rotating magnetic field.

  The center piece 16 includes a support portion 20 and an annular portion 22 formed in an annular shape around the support portion 20. The support portion 20 protrudes from the annular portion 22 to one side in the axial direction of the center piece 16. The support portion 20 is formed in an annular shape (tubular shape) and is provided around the shaft 12. The shaft 12 is press-fitted inside the support portion 20, and the shaft 12 is supported by the inner peripheral portion 20 </ b> A of the support portion 20. The support portion 20 is press-fitted inside the stator core 14, and the stator core 14 is held by the outer peripheral portion 20 </ b> B of the support portion 20.

  A circular groove 24 along the circumferential direction of the support portion 20 is formed at the end portion on the one side in the axial direction of the support portion 20. The groove 24 is open on one side in the axial direction of the support portion 20. An inner wall portion 26 is formed between the groove 24 and the inner peripheral portion 20A of the support portion 20, and an outer wall portion 28 is formed between the groove 24 and the outer peripheral portion 20B of the support portion 20. ing.

  The support portion 20 is formed with a communication hole 30 extending along the axial direction of the support portion 20. One side in the axial direction of the communication hole 30 opens to the bottom surface 24 </ b> A of the groove 24, and the other side in the axial direction of the communication hole 30 opens to the end face 20 </ b> C on the other axial side of the support portion 20. A plurality of the communication holes 30 are formed at intervals in the circumferential direction of the support portion 20.

  The annular portion 22 is formed in a plate shape in which the axial direction of the support portion 20 is the plate thickness direction. The annular portion 22 faces an opening 18A on the other axial side of the rotor housing 18 described later. The annular portion 22 is formed with a through hole 32 that penetrates along the axial direction of the support portion 20. A plurality of the through holes 32 are formed at intervals in the circumferential direction of the annular portion 22.

  The rotor housing 18 is formed in a cylindrical shape having an outer cylinder portion 34, an inner cylinder portion 36, and a connecting portion 38. The outer cylindrical portion 34 is disposed on the radially outer side of the stator core 14, and a rotor magnet 40 is fixed to the inner peripheral surface of the outer cylindrical portion 34. The rotor housing 18 and the rotor magnet 40 constitute a rotor 39 that rotates by a rotating magnetic field formed by the stator 15.

  A pair of bearings 42 is accommodated inside the inner cylinder portion 36. The bearing 42 is a ball bearing having an inner ring and an outer ring. The shaft 12 is press-fitted inside the inner ring of the bearing 42, and the outer ring of the bearing 42 is press-fitted inside the inner cylinder portion 36. The inner cylinder portion 36 is supported by the shaft 12 via a pair of bearings 42.

  The inner cylinder part 36 is disposed on one axial side with respect to the support part 20. The inner cylinder portion 36 extends from the one side in the axial direction with respect to the support portion 20 toward the support portion 20, and the distal end portion 44 of the inner cylinder portion 36 is inserted inside the groove 24. The distal end portion 44 of the inner cylinder portion 36 has a gap between the pair of side surfaces and the bottom surface of the groove 24, and a labyrinth structure 46 is configured with the groove 24.

  The connecting portion 38 is formed with the axial direction of the rotor housing 18 as the plate thickness direction, and connects the end portions on one side in the axial direction of the outer cylinder portion 34 and the inner cylinder portion 36. The connection portion 38 is formed with a ventilation hole 48 penetrating along the axial direction of the inner cylinder portion 36. A plurality of ventilation holes 48 are formed at intervals in the circumferential direction of the connecting portion 38.

  Further, a cover 50 is added to the rotor housing 18. The cover 50 is separated from the rotor housing 18 and assembled to the rotor housing 18, or is formed integrally with the rotor housing 18. The cover 50 is formed in a circular plate shape and closes the opening 36 </ b> A on one side in the axial direction of the inner cylinder portion 36.

  The brushless motor 10 having the above configuration is suitably used as a fan motor, for example. For example, a fan 52 is attached to the rotor housing 18. In the present embodiment, the brushless motor 10 is normally arranged with one axial side as the upper side in the vertical direction, and the fan 52 is rotated parallel to the horizontal direction as an example.

  The cooling air W is taken into the motor through the ventilation holes 48 by the blow of the fan 52, and the cooling air W taken into the motor is connected to the communication holes 30, the through holes 32, and the outer cylinder of the rotor housing 18. Each is discharged to the outside of the motor through a gap between the portion 34 and the annular portion 22 of the center piece 16. The cooling air W supplied to the stator core 14 passes between a plurality of teeth formed radially on the stator core 14.

  Further, water droplets enter the motor together with the cooling air W through the ventilation holes 48, and the water droplets that have entered the motor may flow to the support portion 20 side along the outer peripheral surface of the inner cylinder portion 36. Since the distal end portion 44 and the groove 24 of the inner cylindrical portion 36 constitute a labyrinth structure 46, the labyrinth structure 46 prevents water droplets from entering the inner cylindrical portion 36 from the distal end portion 44 side of the inner cylindrical portion 36. The

  Next, the operation and effect of one embodiment of the present invention will be described.

  As described above in detail, according to the brushless motor 10 according to the embodiment of the present invention, the rotor housing 18 is formed with the connecting portion 38 that connects the outer cylinder portion 34 and the inner cylinder portion 36. The connection portion 38 is formed with a ventilation hole 48 penetrating along the axial direction of the inner cylinder portion 36. Therefore, since the cooling air W can be taken into the motor through the ventilation holes 48, the cooling performance inside the motor can be ensured.

  Further, the cooling air inside the motor can be ensured by the cooling air W through the ventilation hole 48, so that it is not necessary to increase the physique of the motor to ensure the cooling performance, and the brushless motor 10 can be downsized. it can.

  Further, the inner cylinder portion 36 extends from the one side in the axial direction with respect to the support portion 20 toward the support portion 20, and a distal end portion 44 of the inner cylinder portion 36 is a groove formed in the support portion 20 of the center piece 16. The labyrinth structure 46 is configured with the groove 24. Therefore, even if water droplets that have entered the motor through the ventilation hole 48 flow to the support portion 20 side along the outer peripheral surface of the inner cylindrical portion 36, the water droplets from the distal end portion 44 side of the inner cylindrical portion 36 to the inner cylindrical portion 36. The labyrinth structure 46 can prevent entry into the inside. Thereby, since the moisture of the bearing 42 can be suppressed, the waterproofness and corrosion resistance of the bearing 42 can be ensured.

  In addition, a communication hole 30 extending along the axial direction of the support part 20 is formed in the support part 20, and one side in the axial direction of the communication hole 30 opens to the bottom surface 24 </ b> A of the groove 24. The other side in the axial direction is open to the end face 20 </ b> C on the other side in the axial direction of the support portion 20. Therefore, even if water droplets that are prevented from entering the inner cylinder portion 36 by the labyrinth structure 46 accumulate in the groove 24, the water droplets can be discharged to the outside through the communication hole 30. Thereby, the moisture of the bearing 42 can be further effectively suppressed.

  Further, the opening 36A on the one axial side of the inner cylinder part 36 is closed by the cover 50, so that water droplets enter the inner cylinder part 36 from the opening 36A on the one axial side of the inner cylinder part 36. The cover 50 can prevent the bearing 42 from being directly exposed to water.

  Further, a through hole 32 that penetrates along the axial direction of the support portion 20 is formed in the annular portion 22 of the center piece 16. Therefore, since the cooling air W taken into the motor can be discharged through the through hole 32, the air permeability inside the motor can be improved, and consequently the cooling inside the motor can be improved.

  Next, a modification of one embodiment of the present invention will be described.

(First modification)
In the said embodiment, the brushless motor 10 may be arrange | positioned upside down as FIG. 2 shows. Therefore, when the brushless motor 10 is disposed upside down, a cover 54 that closes the opening 30 </ b> A on the other axial side of the communication hole 30 may be added to the center piece 16. The cover 54 is separated from the center piece 16 and assembled to the center piece 16 or is formed integrally with the center piece 16.

  In this modification, the cover 50 provided on the rotor housing 18 corresponds to an example of the “first cover” in the present invention, and the cover 54 provided on the center piece 16 is the “second cover” in the present invention. Is equivalent to an example.

  According to this modification, as shown in FIG. 2, even when the brushless motor 10 is arranged upside down, the cooling air W is taken into the motor through the through hole 32 formed in the annular portion 22. Since the cooling air W taken into the motor is discharged to the outside of the motor through the ventilation holes 48, the cooling performance inside the motor can be secured.

  Further, when the brushless motor 10 is disposed upside down, there is a risk that water droplets may enter the motor through the through hole 32. However, as described above, the distal end portion 44 and the groove 24 of the inner cylinder portion 36 are provided with a labyrinth structure. 46, the labyrinth structure 46 can prevent water droplets from entering the inner cylinder portion 36 and the bearing 42 from getting wet.

  Further, since the opening 30A on the other axial side of the communication hole 30 is closed by the cover 54, the opening 30A on the other axial side of the communication hole 30 can be used even when the brushless motor 10 is disposed upside down. The cover 54 can prevent water droplets from entering and the bearing 42 from being directly exposed to water.

  Further, by adding the cover 54, the brushless motor 10 can be arranged upside down, so that the degree of freedom of mounting the brushless motor 10 can be increased.

(Second modification)
As shown in FIG. 3, for example, when a fan 52 is attached to the rotor housing 18, and the fan 52 rotates together with the rotor 39 including the rotor housing 18 and the rotor magnet 40, the rotating unit including the rotor 39 and the fan 52. In contrast, buoyancy F1 (payload force) in one axial direction may occur. As described above, when the buoyancy F1 to the one side in the axial direction is generated with respect to the rotating portion, the force F2 to the one side in the axial direction acts on the bearing 42, and the rotor 39 moves together with the bearing 42 to the one side in the axial direction. There is a risk of it.

  Therefore, in this modification, as shown in FIG. 4, the axial center portion 40 </ b> A of the rotor magnet 40 is shifted to one axial side (arrow A <b> 1 side) with respect to the axial center portion 14 </ b> A of the stator core 14. ing. As described above, as a method of shifting the axial center portion 40 </ b> A of the rotor magnet 40 toward the one axial side with respect to the axial center portion 14 </ b> A of the stator core 14, the rotor magnet 40 with respect to the outer cylinder portion 34 of the rotor housing 18. The position of the stator core 14 relative to the support portion 20 of the center piece 16 may be shifted to the other side in the axial direction (arrow A2 side).

  As described above, when the axial center portion 40A of the rotor magnet 40 is shifted to one axial side with respect to the axial center portion 14A of the stator core 14, the other axial direction from the stator core 14 to the rotor magnet 40 is obtained. Since the suction force F3 to the side, that is, the side opposite to the above-described buoyancy F1, acts, the movement of the rotor 39 to one side in the axial direction can be suppressed.

  Thereby, it is possible to prevent the rotor 39 from coming off, improve the reliability, maintain the labyrinth structure 46, and improve the waterproof reliability of the bearing 42. Furthermore, the thrust load (force F2) acting on the bearing 42 can be reduced, the life of the bearing 42 can be improved, and the press-fit dimension of the bearing 42 and the shaft 12 can be reduced.

(Other variations)
In the above embodiment, the fan 52 is fixed to the rotor housing 18 as an example, but may be fixed to the shaft 12.

  Moreover, in the said embodiment, although the brushless motor 10 is used as a fan motor, you may be used as motors other than a fan motor.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and other various modifications can be made without departing from the spirit of the present invention. It is.

DESCRIPTION OF SYMBOLS 10 ... Brushless motor, 12 ... Shaft, 14 ... Stator core, 15 ... Stator, 16 ... Centerpiece, 18 ... Rotor housing, 20 ... Support part, 20A ... Inner peripheral part, 20B ... Outer peripheral part, 22 ... Annular part, 24 ... Groove, 30 ... communicating hole, 32 ... through hole, 34 ... outer cylinder part, 36 ... inner cylinder part, 38 ... coupling part, 39 ... rotor, 40 ... rotor magnet, 42 ... bearing, 44 ... tip part, 46 ... labyrinth Structure: 48 ... vent hole, 50 ... cover (first cover), 52 ... fan, 54 ... cover (second cover)

Claims (5)

A shaft,
An annular stator core provided coaxially with the shaft;
Provided in an annular shape around the shaft, supporting the shaft at the inner periphery and holding the stator core at the outer periphery, and forming the support portion in a circular shape along the circumferential direction of the support And a center piece having a groove opened on one side in the axial direction of the support part;
An outer cylinder portion that is disposed on the radially outer side of the stator core and has a rotor magnet fixed to an inner peripheral surface thereof, and is supported by the shaft via a bearing, and from the one side in the axial direction to the support portion to the support portion. An inner cylindrical portion that extends toward the inner end of the groove and forms a labyrinth structure with the groove, and ends on one axial side of the outer cylindrical portion and the inner cylindrical portion. A rotor housing having a coupling portion formed with a ventilation hole penetrating along the axial direction of the inner cylinder portion, and
Brushless motor with The support portion is formed with a communication hole extending along the axial direction of the support portion, one side in the axial direction opening on the bottom surface of the groove, and the other side in the axial direction opening on the end surface on the other side in the axial direction of the support portion. Being
The brushless motor according to claim 1. A cover for closing the opening on the one axial side of the inner tube portion;
The brushless motor according to claim 2. A first cover as the cover;
A second cover for closing the opening on the other axial side of the communication hole;
With
The center piece is formed in an annular shape around the support portion, and has an annular portion facing the opening on the other axial side of the rotor housing,
A through-hole penetrating along the axial direction of the support portion is formed in the annular portion.
The brushless motor according to claim 3. The axial center portion of the rotor magnet is shifted to one axial side with respect to the axial center portion of the stator core.
The brushless motor as described in any one of Claims 1-4.

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