JP2001061264A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce man-hours in manufacturing and cost, and also to enhance heat radiation (heat lead-out) effect and waterproofness. SOLUTION: A center piece 3 is formed integrally into the shape of a cup by pressing a metallic plate material. An open end 3b is extended from the periphery of the bottom section 3a of the center piece 3. A cylindrical part 3b is projected outward from the center of the bottom 3a. The bottom 3a is fixed to a motor bracket 1 with a screw 12, pinching an O-ring 11 inbetween for waterproofing. Moreover, a yoke 9 of a rotor 7 is covered with the open end 3b of the center piece 3. A fan 16 is fixed to a yoke 9, and a boss 16a of the fan 16 is constituted so as to wrap in the open end 3b of the center piece 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer rotor type brushless motor particularly suitable for a blower motor of a vehicle cooling system.

[0002]

2. Description of the Related Art The present applicant has previously proposed various outer rotor type brushless motors suitable for a blower motor of a vehicle air conditioner. In this outer rotor type brushless motor, a stator is fixed to an upper surface of a motor holder.
The stator includes a center piece and a core supported by the center piece and wound with a winding.

[0003] The center piece includes a flange portion and a substantially cylindrical shaft support portion for holding the core. A pair of upper and lower supporting recesses for holding the two bearings is formed on the inner peripheral surface of the shaft supporting portion. The two bearings held by the supporting recesses rotatably support a rotating shaft to which the rotor is fixed. In other words, the center piece supports the stator and rotatably supports the rotating shaft.

[0004] In order to reduce the cost of this type of brushless motor, it is conceivable to form the centerpiece with a synthetic resin. However, the centerpiece made of a synthetic resin does not provide much accuracy and has rigidity (strength). ) Is low, the wall thickness needs to be increased, and the size of the entire motor may increase. In addition, since the heat conductivity of the synthetic resin is poor, there is a problem that heat generated by the winding of the stator via the center piece can hardly be radiated. Therefore,
In order to improve strength, accuracy and heat radiation, the center piece was made of aluminum alloy and was formed by die casting.

However, the molding accuracy of the die casting method is limited, and the center piece formed by aluminum die casting has a supporting recess (inner hole) for fitting and holding the two bearings.
In order to improve the accuracy (concentricity) of the support, it was necessary to perform cutting processing on the supporting concave portion (inner hole). Then, the applicant made the center piece to be processed with high precision by pressing,
A device for improving the precision of forming the centerpiece has been filed (Japanese Patent Application No. 10-191743).

[0006]

By the way, when this kind of conventional brushless motor is applied to a motor for a blower of a vehicle cooling system, the heat dissipation (heat extraction) effect by a center piece is insufficient, so that a further heat dissipation is required. (Derived heat)
A brushless motor having a centerpiece having an effect is expected. Further, in the conventional brushless motor of this type, since there is no waterproof measure, there is a possibility that water such as rainwater may enter the motor along the motor holder.

An object of the present invention is to provide a brushless motor capable of reducing the number of manufacturing steps and costs, and improving the heat radiation (heat extraction) effect and waterproofness.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 includes a bottom part fixed to a motor holder and a cylindrical part protruding from the center of the bottom part. A brushless motor comprising: a center piece having: a stator core attached outside the cylindrical portion; and a rotor having a yoke surrounding the stator core and having a plurality of magnets fixed to an inner surface thereof. The gist is that a wall portion that covers the yoke of the rotor extends from an outer peripheral portion of the bottom surface portion.

According to a second aspect of the present invention, in the brushless motor according to the first aspect, an axial fan for blowing air having a boss portion is fixed to a top end surface of the yoke, and a wall portion of the center piece is provided. The gist of the present invention is to cover the boss of the fan and to be located between the boss and the yoke.

[0010] The invention described in claim 3 is the invention according to claim 1 or 2.
Wherein the center piece is formed by press working. According to a fourth aspect of the present invention, in the brushless motor according to any one of the first to third aspects, the center piece has a bottom surface fixed to the motor holder with a sealing material interposed therebetween. And

(Operation) According to the first aspect of the present invention,
The centerpiece has a wall portion extending from the outer peripheral portion of the bottom portion to cover the yoke of the rotor. Therefore, the heat generated by the stator is quickly transmitted to the wall portion via the cylindrical portion and the bottom portion of the center piece, so that the heat radiation (heat extraction) effect of the brushless motor can be improved.

According to the second aspect of the invention, the wall of the center piece is covered with the boss of the fan and is located between the boss and the yoke of the rotor. Therefore, in addition to the effect of the invention as defined in claim 1, the wall can be efficiently cooled by the fan, and when water such as rainwater enters the brushless motor, the water is reduced by the boss in the wall. Is prevented from penetrating. as a result,
The waterproofness of the brushless motor can be improved.

According to the third aspect of the present invention, the first aspect is provided.
In addition to the effects of the inventions described in (1) and (2), since press working is a kind of high-precision forming work, the forming accuracy of the center piece formed by press working can be improved. As a result, it is possible to reduce the number of manufacturing steps and processing cost of the brushless motor.

According to the invention described in claim 4, according to claim 1 of the present invention,
In addition to the functions of the inventions described in the above-mentioned items, the center piece is
The bottom surface is fixed to the motor holder with a sealing material interposed.

Therefore, when water such as rainwater enters the brushless motor, the water is prevented from entering along the bottom surface of the motor holder and the center piece. As a result, the waterproofness of the brushless motor can be further improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an outer rotor type brushless motor used as a blower motor of a vehicle air conditioner will be described below with reference to FIGS.

As shown in FIG. 1, a brushless motor M
Is the upper surface 1 of the motor bracket 1 as a motor holder.
The stator 2 is fixed at the center position of a. The stator 2 includes a center piece 3, a core 4, and a winding 5.

The center piece 3 is integrally formed in a cup shape with a bottom by pressing a plate material of a metal material (for example, iron alloy or steel), and has a bottom portion 3a and the bottom portion 3a.
A large-diameter open end 3b extending upward from the outer peripheral portion of
Flange 3c expanding from the tip of open end 3b
And a small-diameter cylindrical portion 3d projecting upward from the center of the bottom portion 3a. That is, the cylindrical portion 3d is inherent in the open end 3b, and a cylindrical space is formed between the cylindrical portion 3d and the open end 3b.

A plurality of threaded holes 3e are provided at predetermined positions on the bottom surface 3a. The cylindrical portion 3d has a small diameter portion 3f formed at the tip. Inner hole 3g of cylindrical part 3d
Is formed so as to penetrate the bottom surface 3a. A plurality of embossed portions 3h are formed at an axially intermediate position of the cylindrical portion 3d from the outer peripheral surface toward the inner hole 3g. In this embodiment, each of the four embossed portions 3 is divided into upper and lower stages symmetrically with respect to the center axis of the cylindrical portion 3d.
h is formed. As shown in FIG. 1, the embossed portion 3h projects from the inner peripheral surface of the cylindrical portion 3d toward the central axis, and a step 3i is formed.

Then, as shown in FIG. 1, by inserting the cylindrical portion 3d into the inner hole 4a of the core 4, the core 4 is fitted and supported by the cylindrical portion 3d. Inner hole 3 of cylindrical part 3d
g, a pair of first and second bearings 6a,
6b is press-fitted. First and second bearings 6a, 6
Each of b is supported in the axial direction by the step 3i, and the position in the axial direction is also determined.

The first and second bearings 6a, 6b
Has large diameter portions 6c and 6d formed at one end. In FIG. 1, inner holes 6e and 6f serving as rotary shaft insertion holes of the first and second bearings 6a and 6b are formed with large-diameter holes 6g and 6h in portions in the axial direction corresponding to the large-diameter portions 6c and 6d. Have been.

Then, as shown in FIG. 1, the rotating shaft 8 of the rotor 7 is placed from above the stator 2 constructed as described above.
Are rotatably inserted into inner holes 6e and 6f of the first and second bearings 6a and 6b, so that the rotor 7
It is rotatably supported by the stator 2. At this time,
A bell-shaped yoke 9 constituting the rotor 7 is arranged so as to cover the stator 2, and a plurality of magnets 10 fixed to the inner peripheral surface of the yoke 9 are arranged around the core 4. The outer periphery of the yoke 9 is covered by the open end 3b of the center piece 3.

Also, the bottom portion 3a of the center piece 3
Is fixed with a plurality of screws 12 with a waterproof O-ring 11 as a sealing material interposed between the motor bracket 1. A circuit board 13 on which an excitation circuit is mounted is fixed to a lower surface of the motor bracket 1. When an exciting current is supplied from the exciting circuit to the winding 5 of the stator 2, a rotating magnetic field is generated in the stator 2, and the rotor 7 is driven to rotate based on the rotating magnetic field.

As shown in FIGS. 1 and 2, a resin waterproof cover 14 is fixed to the lower surface of the motor bracket 1 with a plurality of screws 15. A plurality of screws 18 are fixed to the top end surface 9a of the yoke 9 of the rotor 7 via a fan centerpiece 17 into which an axial fan 16 for blowing air made of a resin material is inserted. A center boss 16 a as a boss of the axial fan 16 is configured to wrap around the open end 3 b of the center piece 3. That is, the open end 3b is covered by the boss 16a of the fan 16 and is located between the boss 16a and the yoke 9 of the rotor 7.

Next, the features of the brushless motor M configured as described above will be described. (1) In this embodiment, the center piece 3 has an open end 3 covering the yoke 9 of the rotor 7 from the outer periphery of the bottom surface 3a.
b is extended. Therefore, the heat generated in the stator 2 is transmitted to the open end 3b cooled by the axial fan 16 for blowing through the cylindrical portion 3d and the bottom surface 3a of the center piece 3. As a result, the brushless motor M
Can improve the heat dissipation (heat derivation) effect.

(2) In this embodiment, the center piece 3
The open end 3b is covered by a boss 16a of the fan 16 and is located between the boss 16a and the yoke 9 of the rotor 7.

Accordingly, the open end 3b is efficiently connected to the fan 1
6, when water such as rainwater enters the brushless motor M, the boss 16a prevents the water from entering the open end 3b. As a result, the waterproofness of the brushless motor M can be improved.

(3) In this embodiment, the center piece 3
Is formed by press working. Accordingly, the press working is a kind of high-precision forming work, so that the forming accuracy of the center piece 3 formed by the press working can be improved. As a result, the number of manufacturing steps and cost of the brushless motor M can be reduced.

(4) In this embodiment, the center piece 3
The bottom surface 3a is fixed to the motor bracket 1 with a waterproof O-ring 11 interposed therebetween. Therefore, when water such as rainwater enters the brushless motor M, the water flows along the bottom surface 3a of the motor bracket 1 and the center piece 3 on the circuit board 1 disposed on the lower surface of the motor bracket 1.
3 is prevented. As a result, the waterproofness of the brushless motor M can be further improved.

The above embodiment may be modified as follows. In the above embodiment, the center piece 3 is integrally formed by press working with a metal plate material such as an iron alloy or steel, but is excellent in strength (rigidity), heat conductivity, and plastic working (press working). Metal material, for example, copper alloy,
Pressing may be performed using a plate material such as a zinc alloy and stainless steel. In this case, effects similar to the effects described in the features (1) to (4) of the above embodiment can be obtained.

The center piece 3 may be formed by a processing method other than press forming. in this case,
The same effects as those described in the features (1), (2), and (4) of the above embodiment can be obtained.

In the above embodiment, the center piece 3
Was carried out with the bottom surface 3a fixed to the motor bracket 1 with the waterproof O-ring 11 interposed therebetween, but the invention is not limited to the waterproof O-ring 11. Other sealing material, for example, bottom part 3
This may be implemented by a waterproof sealing material having a shape along the contact surface between a and the motor bracket 1. In this case, effects similar to the effects described in the features (1) to (4) of the above embodiment can be obtained.

In the above embodiment, the present invention is embodied in the outer rotor type brushless motor used as the blower motor of the vehicle cooling device, but may be embodied in another brushless motor. In this case, in this case, the same effects as those described in the features (1) to (4) of the above embodiment can be obtained.

Next, technical ideas other than those described in the claims which can be understood from the above embodiment and other examples will be described below together with their effects. (1) The brushless motor according to any one of claims 1 to 4, wherein the center piece is formed of a metal plate.

Therefore, in addition to the effects of the first to fourth aspects of the present invention, the strength and rigidity of the center piece as a skeleton of the entire brushless motor can be improved. Further, heat radiation of the stator is easily performed via the center piece.

(2) A bottom portion (3a) fixed to the motor holder (1) and a projection formed from the center of the bottom portion (3a). The stator core (4) is attached to the outside and the bearing ( 6a, 6b) a cylindrical portion (3) rotatably supporting a rotating shaft (8) on which a fan (16) is mounted.
d), the center piece (3) is formed by press working, and the wall portion covering the yoke (9) of the rotor (7) from the outer peripheral portion of the bottom portion (3a). (3b) A centerpiece of a brushless motor, wherein the centerpiece is extended.

Therefore, it is possible to reduce the number of manufacturing steps and processing cost of the center piece, and it is possible to improve the heat radiation (heat extraction) effect of the brushless motor having the center piece.

[0038]

As described above in detail, according to the first aspect of the present invention, it is possible to reduce the number of manufacturing steps and cost of the brushless motor and to improve the heat radiation (heat extraction) effect of the brushless motor. can do.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in (1), the heat radiation (heat extraction) effect and waterproofness of the brushless motor can be improved. According to the third aspect of the invention, in addition to the effects of the first and second aspects of the invention, the number of manufacturing steps and cost of the brushless motor can be reduced.

According to the invention described in claim 4, according to claim 1 of the present invention,
In addition to the effects of the inventions described in (1) to (3), the waterproofness of the brushless motor can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a brushless motor according to an embodiment.

FIG. 2 is a bottom view of the brushless motor.

[Explanation of symbols]

M: brushless motor, 1: motor bracket as motor holder, 2: stator, 3: center piece, 3
a: bottom portion, 3b: open end portion as a wall portion, 3d: cylindrical portion, 3k: step portion, 4: stator core, 6a, 6b: bearing, 6e, 6f: inner hole as a rotary shaft insertion hole, 6g, 6
h: large-diameter hole, 7: rotor, 8: rotating shaft, 9: yoke,
Reference numeral 10: magnet, 11: waterproof O-ring as a sealing material, 16: axial fan for blowing air as a fan, 16a
... Center boss as boss.

Claims (4)

[Claims] A center piece (3) having a bottom portion (3a) fixed to the motor holder (1) and a cylindrical portion (3d) protruding from the center of the bottom portion (3a); A stator core (4) attached to the outside of the cylindrical portion (3d); and a rotor (7) having a yoke (9) surrounding the outside of the stator core (4) and having a plurality of magnets (10) fixed to an inner surface thereof. In the brushless motor provided, the center piece (3) is characterized in that a wall (3b) that covers a yoke (9) of the rotor (7) extends from an outer peripheral portion of a bottom portion (3a). And a brushless motor. 2. The brushless motor according to claim 1, wherein a top end surface (9a) of the yoke (9) has a boss (16).
a), the wall portion (3b) of the center piece (3) is covered with the boss portion (16a) of the fan (16) so that the boss portion of the fan (16) has the boss portion. A brushless motor which is located between a portion (16a) and the yoke (9). 3. The brushless motor according to claim 1, wherein the center piece (3) is formed by press working. 4. The motor holder (1) according to claim 1, wherein the center piece (3) has a bottom surface (3a) with a sealing material (11) interposed therebetween. A brushless motor characterized by being fixed to a motor.