JPS6143938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small external rotor type electric motor in which a rotor is located on the outer peripheral side of a stator, and particularly to a cooling structure for the electric motor.

The structure of an external rotor type electric motor, in which the rotor is located on the outer circumference of the stator, is such that the bearing is press-fitted into the inner diameter of the stator, or it is integrally joined with the stator using resin, both of which are fixed. This has the disadvantage that the temperature rise is high due to the effect of heat generation in the child part.

The present invention aims to improve the cooling effect by separating the bearing part from the stator part to form a ventilation passage in order to reduce the temperature rise of the electric motor, and by allowing cooling air to flow through this ventilation passage. be.

In the present invention, only the legs of a metal bearing cover having a cylindrical part for holding a bearing metal are embedded in a resin part and integrally connected, and the cylindrical part is separated from the stator part through a predetermined space. A ventilation passage is formed by the cylindrical part and the stator part, and cooling air flows through the ventilation passage. In addition, if blades are provided on the side wall of the rotor, forced ventilation is performed, which further improves the ventilation cooling effect and reduces the temperature rise in the motor windings and bearings.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 9 and FIG. 10 are a full sectional view and a side view showing the structure of an external rotor type electric motor having a conventional structure. 1 is a stator core, after laminating thin silicon steel plates, a coil 2 is wound thereon, and the stator core 1 is held together with a bearing cover 3 in a mold (not shown). Next, mold resin 4 is injected into this mold, and after thermosetting, stator core 1, coil 2, and bearing cover 3 are integrally fixed by mold resin 4 to form a motor stator. Reference numeral 4a denotes a mold mounting leg portion formed of mold resin 4. Reference numeral 5 denotes a rotor core, which is formed integrally with an aluminum die-casting material 7 by laminating thin silicon steel plates and holding it in a casting mold together with an insert 6, and a shaft 8 is press-fitted into the insert 6 to form a rotor. . Next, after press-fitting and fixing the bearing metal 9 to the bearing cover 3, the shaft 8 is inserted into the bearing metal 9, and the bearing cap 10 is fixed to the bearing cover 3.
The outer rotor type electric motor is constructed by press-fitting into the outer rotor type motor. However, the bearing metal 9 had a problem in that the heat from the coil 2 was conducted to the bearing cover 3 through the stator core 1 and the molded resin 4, which raised the temperature of the bearing metal and significantly shortened the life of the bearing. .

The present invention solves this problem,
This will be explained below.

FIGS. 1 and 2 are a sectional view and a side view showing the configuration of an outer rotor type electric motor according to the present invention. In the figure, the bearing cover 3 is usually made of metal and is formed of a cylindrical portion 3a into which a bearing metal 9 is press-fitted and leg portions 3b for holding the bearing cover with molded resin. Then, the stator core 1, coil 2, and bearing cover 3 are held in the mold, and these three parts are hardened with resin 4 to form a stator.

As shown in the figure, the resin 4 extends from the cylindrical portion 3a to the third
As shown in the figure, the leg portions 3b located outward from the distance G are configured to be molded.

Therefore, as shown in FIG. 3, the inner diameter φF of the stator fixed with resin and the outer diameter φE of the cylindrical portion 3a are
A gap G is formed between the
1. The bearing metal 9 is press-fitted into the cylindrical portion 3a of the bearing cover 3 after being integrally fixed. The rotor core 5 is held in a cast mold together with the insert 6 and fixed together with aluminum die-casting material 7, but the exhaust port 14 and the blades 13 are molded at the same time, and the shaft 8 is press-fitted into the insert 6. Fixedly, a rotor is formed. The blade 13 is for sucking the cooling air flow 12 into the ventilation passage 11.
and is discharged from the exhaust port 14. With this configuration, the heat generated from the coil 2 and conducted from the molded resin 4 is minimized by the ventilation passage 11 and the cooling air flow 12, and the heat conducted to the bearing metal 9 is suppressed to a minimum. This makes it possible to reduce the temperature rise of bearings and extend the life of the bearings. Third
FIG. 4 is a diagram of only the stator showing the formation structure of the ventilation passage 11. That is, as described above, by making the outer diameter φE of the cylindrical portion 3a smaller than the inner diameter φF of the stator, it is possible to secure the ventilation passage 11 of φF−φE=gap G. The effect of reducing the temperature of the bearing metal ring 9 is significant. Figures 5 and 6 show bearing cover 3.
The bearing cover 3 is made up of a cylindrical part 3a into which the bearing metal 9 is press-fitted and a leg part 3b, as described above, and is press-formed from a thin iron plate. Figures 7 and 8 show the structure of the rotor. The blades 13 and the exhaust port 14 are made of aluminum die-cast material 7. After molding and fixing them together with the insert 6 in a casting mold, the shaft 8 is press-fitted into the insert 6. It is fixed to form a rotor.

In the above configuration, when the electric motor is rotated, external wind flows through the gap G between the legs 3b as shown in FIG.
The air is sucked in from the ventilation passage 11 as shown by the arrow in FIG. 1, passes around the cylindrical portion 3a, cools the bearing metal 9, and is discharged from the exhaust port 14 of the rotor. At this time, if the rotor is provided with blades 13, external air is forcibly sucked in and discharged, which improves the cooling performance accordingly.

In this way, according to the present invention, a ventilation passage is formed between the outer periphery of the cylindrical part of the bearing cover that supports the bearing and the stator, so that the cooling performance is improved and the temperature rise of the electric motor is improved, especially in the bearing part. The temperature rise of the motor can be reduced, and a long-life external rotor motor can be provided.

According to the present invention, it is possible to reduce the temperature rise in the windings and bearings of the electric motor.In particular, by reducing the outer diameter of the bearing, a large passageway is secured, and the amount of cooling air flowing through the ventilation passageway is reduced. It has a structure that allows for increased cooling, has a large cooling effect on the bearing metal, and has the effect of extending the life of the bearing.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of an electric motor showing an embodiment of the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is a half-sectional view of a stator, and FIG. 4 is a side sectional view of the same. Figure 5 is a sectional view showing the shape of the bearing cover 3 in Figure 1;
A-O-B sectional view in the figure, Figure 6 is the same side view, Figure 7
The figure shows a cross-sectional view of the rotor, a C-O-D cross-sectional view of Figure 8, a side view of the same, and Figures 9 and 10 are a cross-sectional view and side view of a conventional outer rotor motor. It is a diagram. DESCRIPTION OF SYMBOLS 1...Stator core, 2...Coil, 3...Bearing cover, 3a...Bearing cover cylindrical part, 3b...Bearing cover leg part, 4...Mold resin, 4a...Motor mounting part, 4b... Side part, 5... Rotor core, 6... Insert, 7... Aluminum die-cast material, 8... Shaft, 9... Bearing metal, 10
... bearing cap, 11 ... ventilation path, 12 ... cooling air flow, 13 ... blade, 14 ... exhaust port,
φF: Inner diameter of the inner circumference of the stator, φE: Outer diameter of the bearing cover 3.

Claims (1)

[Scope of Claims] 1. A stator core wrapped with a stator coil, a resin part in which the stator core is embedded together with the coils, a bearing cover that holds a bearing metal inserted into the resin part, and a bearing cover that is hardened with the resin. and a rotor rotatably disposed around a stator core, the bearing cover includes a cylindrical part that is inserted inside the stator core and holds the bearing metal, and one end of the cylindrical part. a plurality of legs extending in the radial direction are formed in the cylindrical part, and the resin surrounds the outer legs, the coil, and the stator core leaving a gap G from the cylindrical part,
An external rotor electric motor characterized in that this gap is opened at both ends of the stator to serve as a passage for cooling air.