JP3516518B2 - Brushless motor - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, 25 [mm] ×
The present invention relates to a brushless motor having a square shape of 25 [mm], which is smaller than a conventional smallest brushless motor and is used for a small fan motor or the like.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing the entire structure of a conventional minimum quadrangular brushless motor. The housing 2a of the brushless motor 1a has a quadrangular shape, and the dimension a of one side thereof is about 25 [mm], which is the smallest type of existing motor. The housing 2a is a rectangular synthetic resin box body having a bottom plate 3a on the bottom surface and an open top surface. A cap 4a is fitted on the lowermost surface of the housing 2a to protect each component inside the housing 2a. A hollow cylindrical bearing tower 20a is erected at the center of the bottom plate 3a with its lower end fixed to the bottom plate 3a. The stator 32a includes a stator core 33a, an upper insulator 34a sandwiching the stator core 33a from above and below, and a lower insulator 35a and a coil 36 wound around the stator core 33a via both insulators 34a and 35a.
The bearing tower 20a is fixed to the outer periphery of the bearing tower 20a. On the other hand, the bearing 37 is provided in the bearing tower 20a.
a and 38a are fitted and a central shaft 39a is pivotally supported at the center thereof. A cup-shaped rotor 42 is fixed to the central shaft 39a. A rotor magnet 40 a is fixed via a yoke 41 at a position inside the rotor 42 that faces the stator 32 a. Further, the blade portion 43 is provided on the outer periphery of the rotor 42.
Are integrally formed. The plate-shaped circuit board 28a is fitted around the outer periphery of the base of the bearing tower 20a, and
It is arranged in contact with the lower insulator 35a of 2a. The circuit board 28a has an outer diameter substantially equal to the outer diameter of the rotor 42, and an IC circuit is formed on the circuit board 28a and IC components such as the Hall element 30a and the drive IC 29a are fixed. Further, the conductive pin 2 is provided on the circuit board 28a.
The lower end side of 1a is connected. Further, the conductive pin 2 penetrating the upper and lower insulators 34a and 35a.
A coil 36a is connected to the upper end of 1a.

[0003]

As described above, the brushless motor 1a shown in FIG. 7 is 25 [mm] × 25.
Although each component is housed inside the housing 2a having an extremely small [mm], a smaller brushless motor is required. This is, for example, 20 [mm] x 2
It has a housing area of about 0 [mm].
Various measures are taken to store all the components in such a tiny housing. For example, there is a method in which the blade portion is downsized and the shape of the circuit board 28a, the mounting position of the IC component, and the like are changed accordingly. However, in this case, if the total height of the motor is kept as it is, the number of laminated plates of the lamination of the stator 32a decreases, and the magnetic characteristics deteriorate. Further, if the blade portion is reduced as it is in the structure shown in FIG. 7, it becomes extremely difficult to manufacture, it is difficult to maintain high precision, and the assemblability becomes poor.

The present invention was devised in view of the above circumstances, and is formed in a smaller size than the existing minimum shape, without deterioration in motor characteristics, with high accuracy, and relatively easily manufactured. , It is an object to provide a brushless motor that can be assembled.

[0005]

In order to achieve the above object, the present invention provides a rectangular housing having a bottom plate via an arm near the lower surface of the central portion, and various IC parts mounted on the lower surface of the bottom plate. A circuit board mounted mainly on the lower surface side thereof, a bearing tower projecting upward from the central portion of the bottom plate and fixing the base end portion to the bottom plate, and a stator fixed to the outer peripheral side of the bearing tower. A brushless motor comprising a central shaft pivotally supported in the bearing tower, a rotor yoke of a magnetic body held by the central shaft and surrounding the stator, and a blade portion engaging with the rotor yoke. And the rotor yoke is an annular upper surface portion that covers the upper surface of the stator.
Outer circumference enclose the stator from the outer periphery of the wood and the upper surface member
Yo consists member of the cup shape formed between the outer peripheral member that is integrally formed, the outer periphery of the upper surface member is engaged wear on one end side of the central axis, and the peripheral inner in periphery the stator member A rotor magnet is fixed at a position opposite to
Are, the blade portion is composed only of a cyclic plate portion outer periphery with blades and the vane which is interposed between the inner periphery of the housing Ru is secured to one end of its <br/> of the rotor yoke, the Low
At the boundary between the upper surface member and the outer peripheral member of the yoke.
Is provided with an annular step portion that is recessed on the stator side.
And at least one locking hole is provided on the upper surface of the annular step.
It is provided and corresponds to the locking hole on the lower surface of the annular plate
And at least one locking projection is integrally provided
At the same time, the annular plate portion has an inner peripheral edge in the radial direction.
It is pressed against the outer peripheral surface of the stepped portion, and
The radially outer surface is pressed against the edge portion of the locking hole.
By attaching the blade part to the rotor yoke
It is characterized by being.

[0006]

According to the present invention, the circuit board is not attached to the outer periphery of the bearing tower as in the prior art, the circuit board is provided on the bottom plate of the housing, and the bottom plate and the cap are prevented from interfering with IC components of the circuit board. Form a relief to prevent. Further, the vane portion has an assembled compact structure to simplify the structure of the rotor yoke. With these structures, downsizing can be achieved and the motor characteristics can be maintained.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an axial sectional view showing the overall structure of the brushless motor of the present embodiment, FIG. 2 is a partial sectional view showing the structure of the rotor yoke and the blade portion in FIG. 1, and FIG. 3 is a detail of an engaging portion between the blade portion and the rotor yoke. FIG. 4 is an enlarged partial sectional view showing the structure.
1 is a top view of FIG. 1, FIG. 5 is a bottom view without the cap of FIG. 1, and FIG. 6 is a bottom view of the cap of FIG.

As shown in FIG. 1, the housing 2 of the brushless motor 1 of this embodiment is of a rectangular box type having a bottom plate 3, and as shown in FIGS. 1, 4 and 5, the dimension b of one side. Is a square quadrangle of 20 [mm]. As shown in FIG. 1 and the like, circular opening holes 16 and 17 are formed in the upper and lower surfaces of the housing 2 so that each component can be housed inside. Further, as shown in FIG. 4 and the like, a plurality of (four in the drawing) mounting holes 18 are formed at the four corners of the housing. Further, as shown in FIG. 5, a plurality of arms 19 (three in the figure) are formed on the bottom plate 3 along the radial direction and enter toward the inside of the housing 2.

A bearing tower 20 is provided at the center of the bottom plate 3.
Is fixed at its base end portion and is connected so as to project along the axial direction. Further, as shown in FIG.
A through hole 22 is formed.

As shown in FIG. 1, the cap 4 is fitted on the lowermost surface of the housing 2 and is made of a flat plate member having the same square area of 20 [mm] × 20 [mm] as the housing 2. . As shown in FIGS. 1 and 6, the cap 4 is fitted by fitting the fitting projection 23 into the fitting hole 23 ′ of the housing 2.
It fits in and is done. Further, as shown in FIG. 6, the cap 4 is provided with a clearance 25 for preventing interference between the ring-shaped clearance 24 and the drive IC 29. Further, the same mounting hole 26 as the mounting hole 18 and the through hole 27 of the conductive pin 21 are drilled.

The circuit board 28 is fixed by abutting against the lower surface of the bottom plate 3 of the housing 2 as shown in FIGS.
On the lower surface side of the circuit board 28, IC components such as the drive IC 29 and the Hall element 30, electronic components, etc. are mounted, and lead wire connecting lands 31 are formed.

As shown in FIG. 1 and the like, the stator 32 includes a stator core 33 having a laminated structure, and an upper insulator 34 and a lower insulator 3 that sandwich the stator core 33 between the upper and lower sides.
5 and both insulators 34, 35 on the stator core 33.
The coil 36 is wound around the bottom plate 3 via the lower insulator 35 and is fixed to the outer circumference of the bearing tower 20. Further, the conductive pin 21 is connected to the coil 36.

In the bearing tower 20, upper and lower bearings 3 are provided.
7, 38 are fitted. A central shaft 39 is fitted on the bearings 37 and 38.

Next, the rotor yoke 5 and the blade portion 6 which constitute the rotor will be described. The rotor yoke 5 is the stator 3
An upper surface member 10 that covers the upper surface of 2 and an outer peripheral member 11 that surrounds the outer periphery of the stator 32 are integrally formed by bending, and are formed of a magnetic material. The upper surface member 10 has an annular step portion 1
3 is formed and a long hole 12 for locking is drilled in the vicinity thereof. Further, as shown in FIG. 1, the rotor magnet 40 is fixed to the inner surface of the outer peripheral member 11. The rotor magnet 40 is arranged at a position facing the outer peripheral side of the stator 32. In addition, the upper surface member 10 of the rotor yoke 5
One end of the bush 15 is engaged and held by the bush 15 fitted to the central shaft 39. On the other hand, the blade portion 6 is composed of a blade 7 and an annular plate portion 8. The outer periphery of the annular plate portion 8 on one end side is fixed to the blade 7, and the inner periphery on the other end side of the annular plate portion 8 abuts and engages with the annular step portion 13 of the upper surface member 10. The annular plate portion 8 has a long hole 1 for locking.
A locking protrusion 9 that fits into the protrusion 2 is formed to project. As shown in FIG. 3, the annular plate portion 8 has a shape in which the other end of the annular plate portion 8 is pressed against the annular step portion 13 in a state where the locking projection 9 is pressed against the edge portion 14 of the locking elongated hole 12. Thus, the blade portion 6 is fixed to the rotor yoke 5 side. Further, as shown in FIG. 4, the blades 7 of the blade portion 6 are composed of a plurality of blades (five in the drawing) and are arranged at equal intervals on the outer periphery of the rotor yoke 5.

As described above, the rotor comprises the rotor yoke 5 with the blade portions 6 detachably fitted thereto, and the yoke 4 is provided on the back side of the rotor magnet 40a as in the prior art shown in FIG.
1, the rotor yoke 5 also serves as the yoke 41. Further, the blades 7 are also formed such that the length is formed along the outer periphery of the rotor yoke 5 but the width in the radial direction is formed smaller. As described above, the entire rotor can be formed from a compact and compact structure.

In the case of the brushless motor 1 of this embodiment,
As described above, the circumference of the rotor is small and compact, the circuit board 28 is fixed to the lower surface of the bottom plate 3 of the housing 2, and the IC parts are the opening holes 17 of the bottom plate 3 and the escape portions 24 and 25 of the cap. And so on. Therefore, it can be formed in a small size of 20 [mm] × 20 [mm] and can maintain the height as in the conventional case, and it is not necessary to reduce the number of laminations of the stator 32. Therefore, the motor characteristics can be maintained.
Of course, the cooling of the inside of the housing 2 by the blade portion 6 can be performed without changing the conventional method.

As described above, the brushless motor of the present invention is constructed, but the detailed structure thereof is not limited to the contents of the above-mentioned embodiment, and publicly known techniques are applied.

[0018]

According to the present invention, the following remarkable effects are obtained. 1) The rotor is formed of a rotor yoke having an integral structure in which a rotor magnet is provided inside and a blade portion fixedly fixed to the rotor yoke, and a cap fitted to the lower surface of the housing is provided with a clearance for preventing interference with IC components of the circuit board. By forming the portion, it is possible to make a smaller brushless motor than the smallest conventional brushless motor. 2) Since the size in the height direction does not change with miniaturization, the number of laminated laminations of the stator does not change. Therefore, the motor characteristics do not change. 3) Since the rotor has a small number of parts and is formed from a structure that can be easily attached, cost can be reduced and assemblability is improved.

[Brief description of drawings]

FIG. 1 is an axial sectional view showing the overall structure of an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing the structure around the rotor in FIG.

FIG. 3 is an enlarged partial cross-sectional view showing the detailed structure of an engaged state of a rotor yoke and a blade portion.

FIG. 4 is a top view of FIG.

5 is a bottom view of FIG.

FIG. 6 is a bottom view of the cap of this embodiment.

FIG. 7 is an axial sectional view of a conventional brushless motor.

[Explanation of symbols]

1 brushless motor 2 housing 3 bottom plate 4 cap 5 rotor yoke 6 wings 7 feathers 8 Annular plate 9 Locking protrusion 10 Top member 11 Peripheral member 12 Long hole for locking 13 annular step 14 edge 15 bush 19 arms 20 bearing tower 24 Runaway 25 Runaway 28 circuit board 29 Drive IC 30 Hall element 32 stator 39 central axis 40 rotor magnet

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Claims (3)

(57) [Claims] 1. A quadrangular housing having a bottom plate via an arm near a lower surface of a central portion, a circuit board mounted on the lower surface of the bottom plate and mainly mounting various IC components on the lower surface side thereof, and a central portion of the bottom plate. A bearing tower that is provided so as to project upward from the base plate and fixes its base end to the bottom plate;
A stator fixed to the outer peripheral side of the bearing tower,
A brushless motor including a central shaft pivotally supported in the bearing tower, a rotor yoke of a magnetic body which is held by the central shaft and is disposed so as to surround the stator, and a blade portion which is engaged with the rotor yoke. And the rotor yoke is an annular upper surface member that covers the upper surface of the stator.
Enclose the outer periphery of the stator from the outer periphery of the upper surface member useless
Consists member of the cup shape formed between the outer peripheral member that is integrally formed, said upper surface member is <br/>-engaging one end of said central axis, and wherein the inner peripheral surface of the outer peripheral member A rotor magnet is fixedly attached at a position facing the outer circumference of the stator.
And, wherein the blade portion is composed only of a cyclic plate portion outer periphery with blades and the vane which is interposed between the inner periphery of the housing Ru is secured to one end of the rotor yoke, the Rotayo
The front of the boundary between the upper surface member and the outer peripheral member
An annular stepped portion that is recessed on the stator side is provided,
At least one locking hole is provided on the upper surface of the annular step.
Also, the lower surface of the annular plate portion corresponds to the locking hole.
If at least one locking projection is provided integrally
In both cases, the inner peripheral edge of the annular plate portion is the annular step.
Radius of the locking projection
Direction outer surface is pressed against the edge of the locking hole.
The blade portion is attached to the rotor yoke by
The brushless motor is characterized by 2. The brushless motor according to claim 1, further comprising a cap mounted on the lowermost surface of the housing, wherein the cap has an escape portion for preventing interference with an IC component of the circuit board. 3. The brushless motor according to claim 1, wherein the rotor yoke has one end side fixed to the central shaft side via a bush fitted on the central shaft.