JP2002354723A - Blushless dc motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration detection precision when used in a washing machine, by eliminating deviation when a magnet is fixed to a yoke for improved fixing-position precision, related to a brushless DC motor which comprises a surface magnet rotor and is driven by an inverter. SOLUTION: A plurality of magnets 9 facing the stator 1 are fixed to a yoke 11 by molding with a resin 10, constituting a rotor 12. Related to the rotor 12, a recessed part 13 is formed on the outer peripheral surface near the proximity part of the adjoining magnets 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor having a surface magnet type rotor and driven by an inverter.

[0002]

2. Description of the Related Art Conventionally, when a DC brushless motor of this kind is used in a washing machine, it is configured as shown in FIG. Hereinafter, the configuration will be described.

As shown in FIG. 5, a stator 1 is inscribed and fixed to an outer periphery of a lower portion of a mechanical case 2 of a mechanism for driving a washing machine, and a rotor 3 is located inside the stator 1 and a shaft 4.
It is rotatably supported by. The shaft 4 is connected to a washing shaft 6 via a reduction gear 5, and is connected to a dehydrating shaft 8 provided coaxially with the washing shaft 6 via a clutch mechanism 7, and a stirring blade (not shown) is attached to the washing shaft 6. ), And a washing and dewatering tub (not shown) is mounted on the dehydrating shaft 8 so as to be driven respectively.

[0004] As shown in FIG. 6, the rotor 3 is formed by molding a resin 10 on the outer periphery of a plurality of magnets 9 facing the magnetic poles of the stator 1 and fixing the resin 10 to a yoke 11 fixed to the shaft 4.

[0005]

However, in such a conventional configuration, the arc-shaped dimension of the magnet 9 is
Is fixed to the yoke 11 so that the adjacent magnets 9 do not come into contact with the yoke 11 and do not float. Therefore, when the center portion of the magnet 9 is pressed and resin-molded, the magnet 9 is biased during molding. There is a problem that the fixing position to the yoke 11 varies.

On the other hand, when the washing and dewatering tub is driven at high speed by such a DC brushless motor for dehydration, when the laundry in the washing and dewatering tub is in an unbalanced state, the vibration including the washing and dewatering tub is included. Vibration of the body increases and dehydration cannot be continued.

At this time, a magnetic detecting means (not shown) for detecting the magnetic flux of the magnet 9 is fixed to the outer periphery of the rotor 3, and the time width of the output signal of the magnetic detecting means is detected, whereby the washing and dewatering tub is provided. The magnitude of the vibration of the vibrator including the above can be detected.

However, if the magnet 9 of the rotor 3 is biased and the fixing position to the yoke 11 varies, the time width of the output signal of the magnetic detecting means can be maintained even when the vibrating body including the washing and dewatering tub does not vibrate. And the difference becomes an error when detecting the vibration of the vibrating body including the washing and dewatering tub, and there is a problem that the vibration detection accuracy is deteriorated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. It is an object of the present invention to eliminate the bias when fixing a magnet to a yoke, improve the fixing position accuracy, and improve the vibration detection accuracy when used in a washing machine. The purpose is.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a rotor in which a plurality of magnets facing a stator are fixed to a yoke by resin molding, and the rotor is formed in the vicinity of an adjacent magnet. A concave portion is formed on the outer peripheral surface in the vicinity.

As a result, it is possible to improve the fixing position accuracy by eliminating bias when the magnet is fixed to the yoke.
Vibration detection accuracy when used in a washing machine can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to a first aspect of the present invention comprises a stator and a rotor having a plurality of magnets facing the stator fixed to a yoke by resin molding, wherein the rotor is composed of adjacent magnets. A concave portion is formed on the outer peripheral surface in the vicinity of the adjacent portion. When a plurality of magnets are fixed to the yoke by resin molding, when resin molding is performed in a state in which adjacent portions of adjacent magnets are pressed by a pressing jig, traces of the pressing jig remain as recesses on the outer peripheral surface. Therefore, the fact that there is a concave portion on the outer peripheral surface near the adjacent portion of the adjacent magnet means that the magnet is uniformly arranged on the yoke by the holding jig during resin molding, and there is no deviation in the fixing position of the magnet with respect to the yoke. Can be improved, and the vibration detection accuracy when used in a washing machine can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the concave portions formed on the outer peripheral surface of the rotor have alternately different shapes. Is determined, for example, which one of the N poles is known, and in the case of demagnetization and remagnetization for some reason, remagnetization can be easily performed.

According to a third aspect of the present invention, in the first or second aspect of the invention, the magnet has a substantially arc-shaped cross section.
The radius of the outer peripheral surface is made smaller than the radius of the inner peripheral surface, and the vicinity of both end surfaces of the magnet is formed to be separated from the inner diameter of the stator, and the back induced voltage induced in the stator winding when the rotor is rotated is represented by a sine. It can be close to waves, eliminates torque unevenness, can obtain a large output, can sufficiently secure the insulation distance between the magnet and the stator, and has a boss that fixes the yoke and rotor to the shaft. Can be integrated, and the cost can be reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Components having the same configuration as the conventional example are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 1) As shown in FIG.
Reference numeral 2 denotes a resin 10 formed on the outer periphery of a plurality of magnets 9 facing the magnetic poles of the stator 1 and fixed to a yoke 11 fixed to the shaft 4, and as shown in FIG. A recess 13 is formed on the outer peripheral surface near 9a. Here, the dimension b between the magnet 9 and the outer peripheral surface of the rotor 12 is
About 0.4 mm is provided so that the magnet 9 is not exposed. The arc-shaped dimension of the magnet 9 is such that the magnet 9 is
When it is fixed to 1, it is formed small so that adjacent magnets 9 do not hit and float. Other configurations are the same as the conventional example.

The operation of the above configuration will be described. When the plurality of magnets 9 are fixed to the yoke 11 by resin molding, if the adjacent portions 9a of the adjacent magnets 9 are resin-molded while being held down by a holding jig (not shown), traces of the holding jig are formed on the outer peripheral surface. It remains as the recess 13.

Therefore, the adjacent portion 9a of the adjacent magnet 9
The presence of the concave portion 13 in the vicinity of the outer peripheral surface means that the pressing jig is uniformly arranged on the yoke 11 at the time of resin molding, and the position of the pressing jig can be accurately positioned by a mold, and the magnet 9 Is formed so that the adjacent magnets 9 do not hit and float, and if there is a gap between the adjacent magnets 9, the position can be regulated by the tip of the holding jig, so that accurate positioning is achieved. The magnet 9 can be fixed to the yoke 11 in a state where the above is completed.

That is, there is no bias in the fixing position of the magnet 9 with respect to the yoke 11, and the fixing position accuracy of the magnet can be improved, and the vibration detection accuracy when used in a washing machine can be improved.

(Embodiment 2) As shown in FIGS. 3 (a) and 3 (b), concave portions 13 formed on the outer peripheral surface of the rotor 12 shown in FIG. 1 alternately have concave portions 13a and 13b having different shapes. Provided. Other configurations are the same as those in the first embodiment.

The operation of the above configuration will be described. Since concave portions 13a and 13b having different shapes are alternately provided on the outer peripheral surface of the rotor 12, when the magnetizing of the rotor 12 is performed, if the position is determined, for example, the N pole can be determined,
In the case of demagnetization and re-magnetization for some reason, re-magnetization can be easily performed.

(Embodiment 3) As shown in FIG.
Constitutes a rotor 15 fixed to the yoke 11 by molding a resin 10. The magnet 14 has a substantially arc-shaped cross section and a radius R1 of the outer peripheral surface smaller than a radius R2 of the inner peripheral surface. The shape in which the vicinity of both end surfaces 14a is apart from the inner diameter of the stator 1 is formed. A concave portion 16 which is a trace of the holding jig is formed on the outer peripheral surface of the adjacent magnet 14 near the proximity portion 14a. Other configurations are the same as those in the first or second embodiment.

The operation of the above configuration will be described. Magnet 1
4 has a shape in which the vicinity of both end faces 14a is separated from the inner diameter of the stator 1, the magnetic flux distribution by the magnet 14 is large at the central portion, becomes smaller toward the both end faces 14 a, and the stator winding when the rotor 15 is rotated. The counter-induced voltage induced in the line is close to a sine wave, eliminating uneven torque and obtaining a large output.

Also, the concave portion 1 formed by the holding jig
6, since the magnet 14 is easily exposed, it is necessary to ensure a sufficient insulation distance between the surface of the magnet 14 at the bottom of the recess 16 and the stator 1. By making the shape away from the inner diameter, the magnet 1
1 and the boss 17 for fixing the rotor 15 to the shaft 4 can be integrated, so that the cost can be reduced. it can.

[0025]

As described above, according to the first aspect of the present invention, there is provided a stator and a rotor in which a plurality of magnets facing the stator are fixed to a yoke by resin molding. Since the concave portion is formed on the outer peripheral surface in the vicinity of the adjacent portion of the adjacent magnet, there is no deviation in the fixed position of the magnet with respect to the yoke, and the accuracy of the fixed position of the magnet can be improved. Accuracy can be improved.

According to the second aspect of the present invention, since the concave portions formed on the outer peripheral surface of the rotor are alternately different in shape, if the position is determined when the rotor is magnetized, for example, the N pole can be changed. I know which one, demagnetize for some reason,
In the case of re-magnetization, re-magnetization can be easily performed.

According to the third aspect of the present invention, the magnet has a substantially arc-shaped cross section, the radius of the outer peripheral surface is smaller than the radius of the inner peripheral surface, and the vicinity of both end surfaces of the magnet is separated from the inner diameter of the stator. From this, it is possible to make the counter-induced voltage induced in the stator winding when the rotor is rotated close to a sine wave,
Eliminates torque unevenness and provides a large output.
The insulation distance between the magnet and the stator can be sufficiently ensured, the yoke and the boss for fixing the rotor to the shaft can be integrated, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a DC brushless motor according to a first embodiment of the present invention is incorporated in a mechanism of a washing machine.

2A is a top view of a main part of the DC brushless motor, and FIG. 2B is a side view of a main part of the DC brushless motor.

FIG. 3A is a side view of a main part of a DC brushless motor according to a second embodiment of the present invention. FIG. 3B is a side view of another main part of the DC brushless motor.

FIG. 4 is a main part top view of a DC brushless motor according to a third embodiment of the present invention;

FIG. 5 is a cross-sectional view showing a state in which a conventional DC brushless motor is incorporated in a mechanism of a washing machine.

FIG. 6 is a bottom view of the rotor of the DC brushless motor.

[Description of Signs] 1 Stator 9 Magnet 9a Proximate portion 10 Resin 11 Yoke 12 Rotor 13 Recess

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 29/00 H02K 29/00 Z F-term (Reference) 3B155 AA10 BA04 CB06 HB10 HB11 MA01 MA02 5H002 AA07 AA08 AB07 AC07 AE08 5H019 AA06 AA10 BB29 CC03 CC08 CC09 DD01 EE14 FF01 5H621 GA01 GA04 HH03 JK08 JK15 JK18 5H622 AA03 CA01 CA05 CA10 CB04 CB05 PP05 PP20

Claims (3)

[Claims] 1. A brushless direct current brushless machine comprising: a stator; and a rotor having a plurality of magnets facing the stator fixed to a yoke by resin molding, wherein the rotor has a concave portion formed on an outer peripheral surface near an adjacent portion of an adjacent magnet. motor. 2. The DC brushless motor according to claim 1, wherein the concave portions formed on the outer peripheral surface of the rotor have alternately different shapes. 3. The brushless DC brush according to claim 1, wherein the magnet has a substantially arc-shaped cross section, the radius of the outer peripheral surface is smaller than the radius of the inner peripheral surface, and the vicinity of both end surfaces of the magnet is separated from the inner diameter of the stator. motor.