JPH0713417Y2 - Small fan motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a small fan motor used, for example, in a case where it is mounted on a printed wiring board or the like to blow and cool electronic components, and in particular, a small fan. The present invention relates to improvement of a rotor with blades of a motor.

[Conventional technology]

BACKGROUND ART Conventionally, for example, a brushless motor including a rotor with blades is known as a small fan motor mounted on a printed wiring board or the like to blow and cool electronic components. In the rotor with blades of this small fan motor, for example, a large-diameter through-hole on the top plate side of a cup-shaped rotor yoke that covers the magnetic core on the stator side is formed, and the through-hole is formed by sandwiching the inner peripheral flange portion of the top plate. A synthetic resin rotor molding portion is insert-molded so as to close it, and a plurality of blades are integrally formed on the outer surface of the rotor molding portion so as to stand upright. Such a rotor with blades forms a brushless motor in combination with a stator, and air can be blown directly by rotation of the rotor with blades driven by a motor without using a rotational force transmission mechanism or a dedicated fan. There are uses as small fan motors.

[Problems to be solved by the device]

However, the small fan motor including the bladed rotor having the above configuration has the following problems.

Since the rotor with blades has a structure in which a plurality of blades are vertically formed from a thin resin-molded rotor molding portion that is insert-molded by sandwiching the inner peripheral flange portion of the rotor yoke, a considerable drag force is applied to the blades during rotation. In contrast to this, the supporting force of the blade base is insufficient and the mechanical strength is likely to be insufficient. In particular, the strength of the blades becomes a problem when reducing the size and weight of the rotor yoke.

Also, an adhesive is applied to the inside of the side wall of the rotor yoke, and a ring-shaped drive magnet is fitted and adhered. However, if there is no escape area for the adhesive at the time of attachment, the drive magnet is accurately attached at a predetermined position. There is an inconvenience that cannot be achieved, and improvement is desired.

In view of the above problems, the first object of the present invention is to provide a small fan motor in which the mechanical strength of the blade integrally erected from the rotor molding portion insert-molded in the rotor yoke is improved. It is in. A second object of the present invention is to provide a small fan motor in which a drive magnet can be accurately attached to a predetermined position of a rotor yoke.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a cup-shaped rotor yoke having a side wall and an inner peripheral flange portion having a large-diameter through hole formed on an end surface thereof, which is mounted inside the side wall of the rotor yoke. Drive magnet, a rotor molding part made of resin insert-molded on the end face side of the rotor yoke so as to sandwich the inner peripheral flange part and close the through hole, and to stand integrally on the outer surface of the rotor molding part. In a small fan motor including a bladed rotor having formed and formed blades, a plurality of concave portions are formed at intervals on the inner peripheral surface of the inner peripheral flange portion of the rotor yoke, and resin is formed in these concave portions. It is characterized in that the rotor molding portion is insert-molded so as to be filled, and the base portion of the blade is positioned so as to overlap the concave portion.

Further, the present invention is characterized in that the inner peripheral flange portion of the rotor yoke is formed by bending so that the inner peripheral side thereof is spaced outward from the end face.

[Action]

In the present invention equipped with such means, the rotor molding portion is insert-molded in the rotor yoke in a state where the recess portion of the rotor yoke is filled with resin, and the partial volume of the rotor molding portion at the base of the blade is equal to the resin amount of the recess portion. Since the force is large and the adhesion force (grip force) to the polygonal surface of the recess is strong, the grip strength with respect to the rotor yoke is also increased, so that the mechanical strength of the blade is high.

Also, if the inner peripheral side of the inner peripheral flange portion is bent and formed so as to be spaced outward from the end face, a gap is created between the drive magnet mounted on the inside of the side wall and the rotor molded portion. A pool of adhesive is formed. When the drive magnet is pressed against the adhesive applied to the inside of the side wall of the rotor yoke, excess adhesive escapes to the above-mentioned reservoir, so a uniform adhesive layer is obtained.
Mounting accuracy of the drive magnet is improved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a half sectional view showing a small fan motor according to the present invention, and a brushless motor is used for convenience.

In FIG. 1, a bottomed hollow portion 5 is formed in the central portion of a synthetic resin stator base 3 formed so as to embed the circuit board 1 inside, and an oilless metal is provided in the hollow portion 5. Two bearings 7 consisting of are fixed at intervals. A step portion 9 is formed on the outer periphery of the hollow portion 5 of the stator base 3, a magnetic core 13 having radial salient pole teeth 11 is placed on the step portion 9, and the stator base 3 is fixed by screws 15
It is fixed to. A drive coil 17 is wound around the salient pole teeth 11 of the magnetic core 13, and both ends of the drive coil 17 are connected to the circuit board 1 on which a drive circuit (not shown) is formed.
The rotor shaft 19 supported by the bearing 7 is a bladed rotor.
It is fixed to the rotor molding part 21 made of synthetic resin 28.

As shown in FIG. 2, this bladed rotor 28 has a cup-shaped rotor yoke 23 in which a side wall and an inner peripheral flange portion 27 having a large-diameter through hole 25 in its end face are integrally formed. ,
A large-diameter through hole 25 formed on the top plate side (end surface) of the cup-shaped rotor yoke 23 is closed, and an inner peripheral flange portion 27 facing the through hole 25 is formed.
It has a rotor molding portion 21 that is insert-molded so as to sandwich and grip. A plurality of semicircular recesses 29 are formed in the inner peripheral flange portion 27 of the rotor yoke 23 at intervals, and the inner peripheral side of the inner peripheral flange portion 27 is slightly outside the end surface image as shown in FIG. A rotor forming portion 21 is formed so as to be bent so as to rise toward one side, and has a base portion that holds the inner peripheral flange portion 27 and the concave portion 29.

Inside the side wall of the rotor yoke 23, an annular drive magnet
31 is adhered with an adhesive (not shown) so as to face the tip of the magnetic core 13 with a slight gap therebetween, and the rotor molding member 21 and the drive magnet 31 inside the inner peripheral flange portion 27.
A small space (gap) is formed between these spaces, and this space serves as an escape reservoir 33 for the adhesive (see FIG. 5). That is, the drive magnet 31 is fixed so that the drive magnet 31 is fitted inside the side wall of the rotor yoke 23 to which the drive agent 31 is applied, and when the drive magnet 31 is fitted, the adhesive is pushed and escaped to the reservoir 33. . Therefore, the mounting accuracy of the drive magnet 31 can be improved and the yield can be increased.

On the outer surface of the rotor molding portion 21, as shown in FIG. 4 and FIG. 5, the base portions (root portions) of the plurality of blades 35 are arranged so as to be erected radially integrally so as to overlap with the concave portions 29 of the rotor yoke 23. It is molded. Since the volume of the base portion of the blade 35 is increased by the amount of the resin filled in the recess 29, and the resin adhesive force is increased on the polygonal surface of the recess 29, the rooting of the base portion of the blade 35 is inevitably secured, so The mechanical strength of the blade can be increased.

In the small fan motor including such a rotor with blades, the blades 35 function as fans by the rotation of the rotor yoke 23, and can be used, for example, for cooling electronic components mounted on a board.

[Effect of device]

As described above, in the small fan motor according to the present invention, a plurality of concave portions are formed at intervals on the inner peripheral surface of the inner peripheral flange portion of the rotor yoke, and the concave portions are filled with resin so that the rotor is formed. The molding portion is insert-molded so that the base of the blade is positioned so as to overlap the recess. Therefore, the following effects are obtained.

Since the partial volume of the rotor molding portion at the base of the blade is large by the amount of resin in the recess, and the adhesive force (gripping force) to the polygonal surface of the recess is strong, the grip strength on the rotor yoke is also increased, so the blade machine Strength is high. It is possible to reduce the size and weight of the rotor yoke.

Further, when the inner peripheral side of the inner peripheral flange portion is bent and formed so as to be separated from the end face outward, a gap is created between the drive magnet mounted inside the side wall and the rotor molded portion,
An adhesive reservoir is formed when the drive magnet is bonded.
If you press the adhesive applied to the inside of the side wall of the rotor yoke when installing the drive magnet, the excess adhesive will escape to the above-mentioned reservoir, so that a uniform adhesive layer can be obtained and the drive magnet installation accuracy will be improved. , Yield can be improved.

[Brief description of drawings]

FIG. 1 is a half sectional view showing a small fan motor according to an embodiment of the present invention. FIG. 2 is a perspective view showing a rotor yoke in the same embodiment. FIG. 3 is a half sectional view showing the rotor yoke in the same embodiment. FIG. 4 is a plan view showing the rotor with blades of the same embodiment. FIG. 5 is an enlarged cross-sectional view showing the main parts of the rotor device with blades of the same embodiment. [Explanation of Codes] 1 ... Circuit board 3 ... Stator base 7 ... Bearing 13 ... Magnetic core 17 ... Drive coil 19 ... Rotor shaft 21 ... Rotor molding part 23 ... Rotor yoke 25 ... Through hole 27 ... Inner peripheral flange part 28 ... With blade Rotor 29 ... Recess 31 ... Drive magnet 33 ... Escape reservoir 35 ... Blade.

Claims (2)

[Scope of utility model registration request] 1. A cup-shaped integrally formed side wall and an inner peripheral flange portion having a large-diameter through hole on its end surface, wherein a plurality of recesses are spaced from each other on the inner peripheral surface of the inner peripheral flange portion. And a drive magnet mounted on the inner side wall of the rotor yoke, the inner peripheral flange portion is sandwiched to close the through hole, and the recess is filled so that the rotor yoke is inserted into the end surface side of the rotor yoke. A rotor with blades including: a molded rotor molding portion made of resin; and a blade integrally formed upright on the outer surface of the rotor molding portion at a position where the base portion overlaps the recess. Small fan motor. 2. The small fan motor according to claim 1, wherein the inner peripheral flange portion of the rotor yoke is formed by bending so that the inner peripheral side thereof is separated from the end face outward. motor.