JPH07107725A - Brushless motor - Google Patents

Abstract

PURPOSE:To restrain the nonuniformity of revolution while winding a winding from the outside of a core, and to reduce cost by composing the core of a first core, in which a section oppositely faced to a magnet is constituted integrally and the thin section of the section oppositely faced to the magnet is reinforced by a molding material, and a second core forming a magnetic circuit by an outer circumferential section. CONSTITUTION:A first core consists of a thin section 15a oppositely faced to the outer circumference of a magnet 6 for a rotor, a winding salient pole section 5b and a coupling section 15c with a second core 16, and bonded with the second core 16, thus forming a magnetic circuit. There is the first core on the whole circumference of the magnet 6 in the magnetic circuit, the change of magnetic flux density at the time of non-conduction by the position of the rotor is reduced, and the nonuniformity of revolution can be restrained. A magnetic path at the time of coil conduction passes through the magnet 6 through an air gap 14 by the magnetic saturation of the thin section 15a, and the rotor is given revolving torque. The thin section 15a is reinforced by a resin core 10a. Windings 9 are wound before the second core 16 is incorporated, thus decreasing the manhours of winding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to a coil structure of an inner rotor type motor in general industry.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional motor. In FIG. 3, reference numeral 1 is a shaft, and a bearing 2 and a bearing 3
It is rotatably supported by. The bearing 3 is fixed to the housing 4, and the bearing 2 is similarly fixed to the outer cylinder 5. Reference numeral 6 denotes a magnet that generates a magnetic force, and is fixed to the shaft 1 integrally with the bush 7 that is a fixing member.

Reference numeral 8 is a core forming a magnetic circuit. 14
Is a gap between the magnet 6 and the core 8. Reference numeral 9 denotes a winding that is energized to generate a torque, and a core 8 is provided via a resin core 10 having functions of ensuring insulation and guiding the winding.
It is wound around. Reference numeral 11 is a screw that fixes the core 8 to the housing 4. The coil of the motor is composed of the winding 9, the resin core 10 and the core 8.

On the other hand, 12 is a circuit board on which a hall element 13 which is a sensor for detecting the position of the magnet 6 is arranged. Further, 9 a is a terminal of the winding, which is connected to the circuit board 12.

FIG. 4 is a sectional view taken along the line AA 'in FIG. In FIG. 4, reference numeral 8 a denotes a winding salient pole portion of the core 8 arranged at the outer circumferential facing portion of the magnet 6, and 8 b denotes an outer circumferential portion of the core 8 outside the winding 9.

3 and 4, when not energized, the magnetic circuit formed by the magnet 6, the air gap 14, and the core 8 is stationary at the position of the rotor where the magnetic potential energy is minimum. Here, when the predetermined winding 9 is energized, a magnetic force of N or S is generated in the winding salient pole portion 8a of the core 8, and the attraction / repulsive force of the magnetic force causes the magnet 6 to rotate.

[0007]

However, the above-mentioned conventional example has the following drawbacks. (1) Due to the shape of the winding salient pole portion 8a of the core 8, the difference in magnetic potential energy with respect to the difference in rotor position was large. As a result, the rotation unevenness during rotation is large,
There was also a problem such as a large initial torque. (2) Since the core 8 has the outer peripheral portion 8b, the winding 9 has to be wound from the inner side of the core 8. When the winding is applied from the inner side, the winding is due to the structure of the winding machine. There is a drawback in that it takes time to turn and the cost is high.

Accordingly, it is an object of the present invention to provide a novel motor coil structure which overcomes the above-mentioned drawbacks.

[0009]

In order to achieve the above object, the present invention provides a first core in which a portion facing a magnet is integrally formed, and a thin portion thereof is reinforced by a molding material, and an outer peripheral portion. The coil concept is characterized in that it has a second core forming a magnetic circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of a first embodiment of the present invention. Reference numeral 1 denotes a shaft, which is rotatably supported by a bearing 2 and a bearing 3. The bearing 3 is fixed to the housing 4, and the bearing 2 is similarly fixed to the outer cylinder 5. 6
Is a magnet that generates a magnetic force, and is fixed to the shaft 1 together with the bush 7 that is a fixing member. A circuit board 12 is provided with a hall element 13 which is a sensor for detecting the position of the magnet 6. Further, 9 a is a terminal of the winding, which is connected to the circuit board 12.

Reference numeral 15 is a first core which constitutes a magnetic circuit, and a second core 16 is arranged on the outer peripheral portion thereof. 1
Reference numeral 4 is a gap between the magnet 6 and the core 8, and 10 is a resin core that reinforces the first core 15 and also has an insulating function. Reference numeral 9 is a winding wound around the first core via the resin core 10. Reference numeral 11 is a screw that fixes the second core 16 to the housing 4.

FIG. 2 is a sectional view taken along the line AA 'in FIG. Reference numeral 15a is a thin-walled portion of the first core 15 arranged on the outer peripheral facing portion of the magnet 6, 15b is a winding salient pole portion, and 15c is a joint portion with the second core 16. Reference numeral 16 is a second core that forms a magnetic circuit with the first core, and is joined at the joining portion 15c of the first core. Further, 10a is a part of the resin core that guides the winding of the winding and also has an insulating function with the first core, and is a reinforcing portion that supports the thin portion of the first core.

FIG. 8 is a graph showing the change in magnetic potential energy with respect to the rotation angle of the magnet. 7a
Shows the conventional characteristics, and 7b shows the characteristics of the motor embodying the present invention. Further, ha is the difference between the maximum value and the minimum value of the magnetic potential energy of 7a, which is called cogging.

1 and 2, in the magnetic circuit formed by the magnet 6, the gap 14, the first core 15 and the second core 16 when the current is not applied, the first core 15 is provided all around the outer circumference of the magnet 6. Therefore, the change in the magnetic potential energy depending on the rotor position can be considerably reduced. Therefore, the uneven rotation of the rotor can be suppressed to a very small value, and the initial torque of the rotor is reduced by the amount of this cogging, and the effect is great at low speed rotation.

Next, during energization, when energization is started,
N or S magnetic flux is generated inside the winding salient pole portion 15b of the first core, and the magnetic flux inside the thin portion 15a of the first core becomes large. However, since the cross-sectional area of the thin portion 15a is much smaller than the cross-sectional area of the winding salient pole portion 15b of the first core and the second core 16, the thin portion 15a first undergoes magnetic saturation. When magnetic saturation occurs, the magnetic permeability of the thin portion 15a becomes substantially the same as the magnetic permeability of air with respect to a magnetic flux higher than this, so that the magnetic path due to coil energization passes through the magnet 6 through the air gap 14. , Rotating force is applied to the magnet 6. Further, the thin portion 15a is reinforced by the resin core 10a, and secures sufficient strength as a motor.

By winding the winding 9 before assembling the second core, the winding 9 can be wound at high speed from the outer peripheral direction. As a result, the number of winding steps can be reduced and the cost can be reduced.

(Embodiment 2) FIG. 5 shows Embodiment 2 of the present invention and is a sectional view taken along the line AA 'in FIG. 1
6a is a notch provided in a part of the second core. 15
Reference numeral c is a joint portion of the first core, and the cutout portion 16a is arranged at a position where it abuts on the joint portion 15c.

On the magnetic circuit, the void in the cutout portion 16a is negligible due to the joint portion 15c of the first core.

Further, the first core 15 and the second core 16 can be fitted by press fitting, but the press fitting margin in this case can be absorbed by the notch 16a being slightly widened, and the joints 15c and The magnetic resistance with the second core can also be lowered.

(Embodiment 3) FIG. 6 shows Embodiment 3 of the present invention and is a sectional view taken along the line AA 'in FIG.
Reference numeral 16b is a concave portion provided in the second core, and 15d is a convex portion of the first core arranged so as to be pressed against the concave portion 16b. As a result, the joint position between the first core 15 and the second core 16 is determined, and the magnetic resistance of this portion can be suppressed low.

(Fourth Embodiment) FIG. 7 is a sectional view showing a fourth embodiment of the present invention. In FIG. 7, reference numeral 12 is a circuit board on which an IC (integrated circuit) 17 is mounted. Reference numeral 9b denotes a barbed portion of the end of the winding, which is connected to the terminal member 18 fixed by the resin core 10. The terminal member 18 is connected to the circuit board 12, and the winding is energized from the IC 17 via the circuit board 12 and the terminal member 18. The same applies to a motor incorporating such a drive IC.
The configuration of the present invention shown in can be applied.

[0023]

As described above, according to the present invention, the portion of the core facing the magnet is integrally formed, and the magnetic circuit is formed by the outer periphery and the first core whose thin portion is reinforced by the molding material. By using the second core, the inexpensive motor with less uneven rotation is realized.

Further, by providing the notch in a part of the second core, a reliable and low magnetic resistance coupling is realized between the first core and the second core.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 3 is a cross-sectional view showing a conventional motor.

FIG. 4 is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 5 shows Embodiment 2 of the present invention.
FIG. 9 is a sectional view taken along line AA ′ in FIG.

FIG. 6 shows Example 3 of the present invention.
FIG. 9 is a sectional view taken along line AA ′ in FIG.

FIG. 7 is a cross-sectional view showing a fourth embodiment of the present invention.

FIG. 8 is a graph showing a change in magnetic potential energy with respect to a rotation angle of a magnet.

[Explanation of symbols]

 1 shaft 2, 3 bearing 4 housing 5 outer cylinder 6 magnet 7 bush 9 winding 10 resin core 11 screw 12 circuit board 13 hall element 14 void 15 first core 15a thin portion of the first core 15b winding winding of the first core Pole part 15c Joint part of first core 15d Convex part of first core 16 Second core 16a Cutout part of second core 16b Recessed part of second core 17 IC 18 Terminal member

Claims (3)

[Claims] 1. A shaft rotatably supported, a cylindrical magnet fixed to the shaft so as to form a magnetic circuit in the radial direction, and a plurality of winding salient pole portions insulated by an insulating member. In a brushless motor having a core arranged on the outer peripheral facing portion of the magnet, the core is
The magnet facing portions of adjacent winding salient pole portions are integrally formed by thin portions, and the first core is configured to cover the thin portions with an insulating member, and the winding salient pole portions have outer circumference portions at which the winding salient poles protrude. A brushless motor comprising a second core arranged so as to join the pole portions. 2. The brushless motor according to claim 1, wherein the second core has a cutout portion, and the cutout portion is arranged at a position where it is pressed against the winding salient pole portion of the first core. And brushless motor. 3. The brushless motor according to claim 1, wherein the plurality of convex portions arranged on the first core are joined to the plurality of concave portions arranged on the second core.