JP5708932B2 - Brushless motor, outer rotor type brushless motor and blower - Google Patents

Description

  The present invention relates to a brushless motor, an outer rotor type brushless motor, and a blower (fan motor) using these.

  An OA device such as a personal computer or a copier has a large number of electronic components housed in its housing, and a large amount of heat is generated from the electronic components, which may destroy the electronic components. Therefore, a blower is attached to a vent hole provided in the device casing so as to release the internal heat to the outside of the casing.

In recent years, the demand for low vibration and low noise has been increasing from the market for such blowers. This type of blower (fan motor) has a structure in which a rotor portion having an impeller is exposed.
For this reason, when attaching the blower to the equipment housing, an external force may be applied, such as touching the rotor portion. Even with such an external force, the coupling between the cup-shaped back yoke and the shaft (rotating shaft) may occur. An excessive load may be applied. When such a load is applied, the joint is deformed and the perpendicularity between the shaft and the cup-shaped back yoke is deteriorated. For this reason, when the rotor rotates, the rotation balance of the rotor is lost, causing vibration and noise. It becomes.

By the way, the above blower has a rotor having a structure in which a shaft is coupled (fixed) to the center of a cup-shaped back yoke.
Conventionally, several different structures are known for coupling (rotor coupling structure) between the cup-shaped back yoke and the shaft. The press-fit joint structure described in Patent Document 1 and the die-cast joint structure described in Patent Document 2 are examples, and the outline of these joint structures will be described below.

FIG. 6 is a partial cross-sectional view (rotor cross-sectional view) of the impeller shown in FIG. 1 of Patent Document 1 “Impeller, Fan Device, and Impeller Manufacturing Method”. As shown in the figure, a press-fit coupling structure in which a shaft fixing portion 322a is provided at the center of the plate portion 322 of the cup-shaped back yoke and the rotary shaft 2 is press-fitted and fixed is described (paragraph [0044] in the specification). )
7 is an enlarged view of a main part of the blower sectional view shown in FIG. 1 of Patent Document 2 “Blower”. As shown, here
(1) A motor yoke (cup-shaped back yoke) 11 is coupled to the upper end of the shaft 6 via a boss 12 made of zinc die cast.
(2) A knurled portion 13 is engraved on the joint portion of the shaft 6 with the boss 12 to enhance adhesion when coupled to the boss 12.
Is described (paragraphs [0028] to [0029] in the specification).

JP 2009-264344 A (paragraph [0044], [FIG. 1]) JP 2002-5093 A (paragraphs [0028] to [0029], [FIG. 1])

However, since the rotor coupling structure described in Patent Document 1 is a structure in which the shaft is press-fitted and coupled to the drawn portion of the cup-shaped back yoke, when an external force is applied to the top surface side of the cup-shaped back yoke, the drawing process is performed. The cylindrical portion may be plastically deformed and the perpendicularity of the shaft may be deteriorated.
Further, since the rotor coupling structure described in Patent Document 2 couples the cup-shaped back yoke and the shaft only by die-casting, when a die-cast inner shrinkage occurs near the shaft, the same as described above. When an external force is applied to the top surface side of the cup-shaped back yoke, the perpendicularity of the shaft may be deteriorated.

  The present invention has been made in view of the above circumstances, and can prevent deterioration of the perpendicularity of the shaft even when an external force is applied to the top surface of the back yoke and the like. And providing a blower.

In order to achieve the above object, in the brushless motor according to claim 1, a bearing is disposed in a housing, a cup-shaped back yoke is fixed to a shaft supported by the bearing, and a permanent magnet is mounted on the cup-shaped back yoke. Is a brushless motor in which a stator is disposed on the side facing the permanent magnet, and the shaft is press-fitted and coupled to the cylindrical portion of the throttle hole of the cup-shaped back yoke, and the shaft press-fitted coupling portion The cup-shaped back yoke is fixed to the shaft by die-casting the shaft and the cup-shaped back yoke so as to cover the shaft.
The brushless motor according to claim 2 is the brushless motor according to claim 1,
An annular recess having a through hole is formed around the cylindrical portion of the throttle hole of the cup-shaped back yoke, and die casting is performed so as to cover the shaft press-fitting joint portion including the annular recess, The shaft and the cup-shaped back yoke are die-cast joined.
The outer rotor type brushless motor according to claim 3 is characterized by using the brushless motor according to claim 1 or 2, wherein the permanent magnet is fixed to an inner peripheral surface of the cup-shaped back yoke. .
A blower according to a fourth aspect is characterized by using the brushless motor according to the first or second aspect or the outer rotor type brushless motor according to the third aspect.

According to the first aspect of the present invention, the cup-shaped back yoke is fixed to the shaft so as to cover the press-fit coupling of the shaft to the cylindrical portion of the throttle hole formed in the cup-shaped back yoke and the shaft press-fit coupling portion. Since the die-casting is performed by die-casting performed, the cup-shaped back yoke can be fixed to the shaft with high strength. Therefore, even when an external force is applied to the top surface of the cup-shaped back yoke, etc. during manufacturing, particularly during assembly or when mounting to a completed device, the perpendicularity of the shaft can be prevented, and low vibration and low A noiseless brushless motor can be provided.
In the invention according to claim 2, an annular recess having a through hole is formed around the cylindrical portion of the throttle hole of the cup-shaped back yoke, and die casting is performed so as to cover the shaft press-fitting joint portion including the annular recess. Then, the shaft and the cup-shaped back yoke are die-cast joined. According to this, it is possible to further increase the strength around the throttle hole cylindrical portion and the bonding strength between the die cast processed portion and the cup-shaped back yoke by die casting.
According to the invention of claim 3, the cup-shaped back yoke is fixed to the shaft so as to cover the press-fit coupling of the shaft to the cylindrical portion of the throttle hole formed in the cup-shaped back yoke and the shaft press-fit coupling portion. Since the die-casting is performed by die-casting performed, the cup-shaped back yoke can be fixed to the shaft with high strength. Therefore, even when an external force is applied to the top surface of the cup-shaped back yoke, etc. during manufacturing, particularly during assembly or when mounting to a completed device, the perpendicularity of the shaft can be prevented, and low vibration and low A noise outer rotor type brushless motor can be provided. Further, it is possible to provide an outer rotor type brushless motor capable of further increasing the strength around the cylindrical portion of the throttle hole and the bonding strength between the die cast processed portion and the cup-shaped back yoke by die casting.
According to the invention according to claim 4, even when an external force is applied to the top surface of the cup-shaped back yoke or the like at the time of manufacture, particularly at the time of assembly or attachment to the completed device, the perpendicularity of the shaft is deteriorated. Therefore, it is possible to provide a low vibration and low noise blower.

It is a front view which shows 1st Embodiment of the air blower which concerns on this invention. FIG. 2 is a cross-sectional view taken along the line II-O-II in FIG. 1. It is a figure which takes out and expands and shows the rotor part in FIG. It is sectional drawing which shows 2nd Embodiment of the air blower which concerns on this invention. It is a figure which takes out and expands and shows the rotor part in FIG. It is sectional drawing which shows the rotor coupling | bonding structure (press-fit coupling structure) of the conventional air blower. It is sectional drawing which shows the rotor coupling | bonding structure (die-cast coupling | bonding structure) of another conventional air blower.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
FIG. 1 is a front view showing a first embodiment of a blower (outer rotor type blower) to which a brushless motor according to the present invention, specifically, an outer rotor type brushless motor is applied, and FIG. 2 is a view taken along the line II-O in FIG. It is -II sectional view taken on the line arrow (blower sectional drawing).
In both figures, 1 is a substantially cylindrical casing made of synthetic resin or the like, and has a venturi 1a formed on the inner periphery. A base 2 is integrally formed at the central portion of the casing 1, and a cylindrical housing 3 is formed at the central portion so as to extend in the casing axial direction.
The outer ring of the two ball bearings 4 and 5 is supported inside the housing 3 with a space therebetween, and the shaft 6 is supported on the inner ring of the ball bearings 4 and 5. A retaining ring 7 is attached to the lower end of the shaft 6 so that the shaft 6 is prevented from being pulled out and positioned in the axial direction.

Reference numeral 8 denotes an impeller made of a synthetic resin or the like, in which blades 10 are formed on the outer periphery of a cup-shaped hub 9. The impeller 8 is fixed to the cup-shaped back yoke 11 by fitting the hub 9 into the outer periphery of the cup-shaped back yoke 11.
The cup-shaped back yoke 11 is coupled and fixed to the shaft 6 by a composite rotor coupling structure of a press-fit coupling structure and a die-cast coupling structure.
That is, as shown in an enlarged view in FIG. 3, the cup-shaped back yoke 11 has a throttle hole cylindrical portion 11b at the center portion of the substantially circular top surface 11a. On the other hand, the shaft 6 is formed in a substantially round bar shape, has a non-concave surface portion 6a at least at one end portion, and has a knurled portion 6b adjacent to the other end side of the shaft 6 of the non-concave surface portion 6a.

Such a non-concave surface portion 6 a at one end of the shaft 6 is press-fitted and coupled to the throttle hole cylindrical portion 11 b formed in the cup-shaped back yoke 11. Further, die casting is performed so as to cover the outer periphery of the shaft press-fit coupling portion, and one end of the shaft 6 and the cup-shaped back yoke 11 are die-cast coupled.
Thereby, the cup-shaped back yoke 11 is coupled to one end of the shaft 6 by a composite rotor coupling structure of a press-fit coupling structure and a die-cast coupling structure, and is fixed to the shaft 6 with high strength.

Here, when the die-casted portion 12 is referred to as a die-cast processing portion, the die-cast processing portion 12 functions to die-cast the shaft 6 and the cup-shaped back yoke 11 as described above. At the same time, it functions as a boss for reinforcing the throttle hole cylindrical portion 11b of the cup-shaped back yoke 11.
The die casting process is performed including the knurled portion 6 b of the shaft 6. Therefore, the knurl part 6b is located on the joint surface with the die cast processed part (boss part) 12, and the shaft 6 and the die cast processed part 12 and further the cup-shaped back yoke 11 at the die cast joined part. The bond strength, particularly the bond strength in the direction around the axis of the shaft 6 is increased.
For die casting, aluminum die casting or zinc die casting is used.

  Returning to FIG. 2, a coil spring 18 is interposed between the inner ring of the ball bearing 4 and the die-casting portion (boss portion) 12, and the die-casting portion 12, in other words, the impeller 8. In addition, an upward biasing force is given in the figure.

A ring-shaped permanent magnet 14 is fixed to the inner periphery of the cup-shaped back yoke 11, and a stator 17 having a stator core 16 and a stator winding 15 is disposed on the inner side of the permanent magnet 14. ing. The stator 17 is fixed to the outside of the housing 3.
Below the stator core 16 (stationary portion), a predetermined current is supplied to the stator winding 15 so that the stator winding 15 and the stator core 16 side and the cup-shaped back yoke 11 and permanent magnet 14 side are connected to the brushless DC motor. A circuit board (not shown) on which an electronic circuit for operating as a stator and a rotor is mounted is attached.

The blower configured as described above is used by being attached to a vent hole of a housing (not shown) of the OA device. The air holes are attached with the lower side in FIG. 2 facing the outside of the housing and the shaft 6 facing in the horizontal direction.
In this state, when a DC power source having a predetermined voltage is supplied to a lead wire (not shown), a current controlled by the electronic circuit on the circuit board flows through the stator winding 15. As a result, a magnetic flux flow is generated from the stator iron core 16, and the cup-shaped back yoke 11 and the impeller 8 rotate around the shaft 6 by the mutual magnetic action of this magnetic flux flow and the magnetic flux flow generated by the permanent magnet 14.
As a result, the air on the upper side in the figure, that is, inside the casing, is sucked and discharged to the lower side in the figure, that is, outside the casing through the wind tunnel 19 formed inside the casing 1. With such an air blowing operation, heat dissipation inside the housing is performed.
When the upper side in FIG. 2 is attached to the outside of the casing, the inside of the casing is cooled by blowing air outside the casing into the casing.

According to the first embodiment of the present invention described above, the cup-shaped back yoke 11 is coupled to the shaft 6 by the composite rotor coupling structure of the press-fit coupling structure and the die-cast coupling structure as described above. The back yoke 11 can be fixed to the shaft 6 with high strength.
Therefore, even when an external force is applied to the top surface 11a of the cup-shaped back yoke 11 during the manufacture of the blower, particularly during assembly or attachment to a completed OA device, the deterioration of the perpendicularity of the shaft is prevented. It is possible to reduce vibration and noise of the blower.

  The die-casting portion 12 functions for die-casting the shaft 6 and the cup-shaped back yoke 11 as described above. At the same time, the die-cast processing portion 12 can be used as a boss portion for reinforcing the throttle hole cylindrical portion 11b of the cup-shaped back yoke 11. Function. Therefore, plastic deformation of the throttle hole cylindrical portion 11b can be effectively prevented.

  Further, die casting was performed including the knurled portion 6 b of the shaft 6. That is, since the shaft 6 is coupled to the die-cast processed portion 12 via the knurled portion 6b, the coupling strength between the shaft 6 and the die-cast processed portion 12, and thus the cup-shaped back yoke 11, particularly the shaft 6 shaft. The coupling strength in the circumferential direction is further increased, and the effect of preventing the deterioration of the perpendicularity of the shaft can be further increased.

Next, another embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view showing a second embodiment of a blower to which a brushless motor according to the present invention is applied, and FIG. 5 is an enlarged view of a rotor portion in FIG.
In the second embodiment, as is apparent from FIG. 5, an annular recess 21 is formed around the throttle hole cylindrical portion 11 b of the cup-shaped back yoke 11, and one or more through holes 22 are formed in the annular recess 21. It is installed.

Then, in the surrounding structure of the throttle hole cylindrical portion 11b of the cup-shaped back yoke 11, die casting is performed so as to cover the outer periphery of the shaft press-fitting joint portion including the annular recess 21, and one end portion of the shaft 6 and the cup The back yoke 11 is die-cast coupled.
As in the first embodiment, the non-concave surface portion 6a at one end of the shaft 6 is press-fitted to the throttle hole cylindrical portion 11b of the cup-shaped back yoke 11.

  According to the second embodiment, through the through hole 22, die casting can be easily performed over the upper and lower sides in the figure of the annular recess 21 around the throttle hole cylindrical portion 11 b, and the cup-shaped back yoke 11 is drawn into the throttle hole. Die-casting can be performed in the form of being sandwiched in the axial direction around the cylindrical portion 11b. Therefore, it is possible to further increase the strength around the throttle hole cylindrical portion 11b and the bonding strength between the die cast processed portion 12 and the cup-shaped back yoke 11 as compared with the die cast processing in the first embodiment.

  A brushless motor (outer rotor type brushless motor) is configured by excluding the impeller 8 and the casing 1 from the configuration of the blower described above and adapting the base 2, the shaft 6, and the like for the motor. In this case, the cup-shaped back yoke 11 and the permanent magnet 14 form the main structure of the rotor, and the stator winding 15 and the stator iron core 16 form the main structure of the stator 17 in the case of the outer rotor type blower described above. It is the same. According to such a brushless motor, the same effect as the above-described blower (outer rotor type blower) can be exhibited.

  In addition, this invention is not limited to the said embodiment, Of course, the deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. reach this invention. For example, the bearing may be a sliding bearing, and the number of sliding bearings may be one.

  1: casing, 3: housing, 4, 5: ball bearing, 6: shaft, 8: impeller, 11: cup-shaped back yoke, 11b: throttle hole cylindrical portion, 12: die cast processed portion (boss portion), 14: Permanent magnet, 15: stator winding, 16: stator iron core, 17: stator, 21: annular recess, 22: through hole.

Claims (4)

A bearing is disposed in the housing, a cup-shaped back yoke is fixed to the shaft supported by the bearing, a permanent magnet is fixed to the cup-shaped back yoke, and a stator is disposed on the side facing the permanent magnet. A brushless motor,
The shaft is press-fitted and coupled to the cylindrical portion of the throttle hole of the cup-shaped back yoke, and die-casting is performed so as to cover the shaft press-fitted joint, and the shaft and the cup-shaped back yoke are die-cast coupled. Thus, the cup-like back yoke is fixed to the shaft.   An annular recess having a through hole is formed around the cylindrical portion of the throttle hole of the cup-shaped back yoke, and die casting is performed so as to cover the shaft press-fitting joint portion including the annular recess, The brushless motor according to claim 1, wherein a shaft and the cup-shaped back yoke are die-cast joined.   An outer rotor type brushless motor using the brushless motor according to claim 1 or 2, wherein the permanent magnet is fixed to an inner peripheral surface of the cup-shaped back yoke.   A blower comprising the brushless motor according to claim 1 or 2, or the outer rotor type brushless motor according to claim 3.

Images