JPS5947536B2 - Bearing device for rotor external rotor type small electric motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing device for a small electric motor with an external rotor.
In particular, it relates to a bearing device for a rotor-outer rotor type small electric motor used in a fan electric motor, etc. In recent years, as a small electric motor used for room air conditioners and ventilation fans, the shape has been reduced to reduce manufacturing costs. In recent years, electric motors with stators molded with resin, such as external rotor type electric motors, are being used.

In such a mold type electric motor, the iron core and the entire winding that constitute the stator are hardened with resin, and at the same time, a part of the stator is equipped with a ball bearing with grease lubrication or an oil-impregnated ball bearing with wick lubrication as a bearing device. Constructed by press-fitting a sintered bearing.

Therefore, the voids in the iron core and windings of a molded motor are filled with resin, which improves thermal conductivity compared to motors with conventional steel plate frames, making it easier for the overall heat to be radiated to the outside air. Therefore, there is an advantage that the temperature rise in the windings is reduced.

However, on the other hand, since the heat generated by the windings is well transmitted to the bearing device, the temperature of the bearing increases.

However, since this type of electric motor bearing device is used for long periods of time without replenishment, when the temperature of the bearing increases, oxidation deterioration of the lubricating oil is promoted, and the loss of evaporation increases, resulting in wear and tear on the bearing. This causes depletion of lubricating oil and shortens its lifespan.

In particular, in the case of oil-impregnated sintered bearings, which are currently widely used as low-noise, inexpensive bearings, if the bearings are used at high temperatures, the above-mentioned deterioration of the lubricating oil and increase in evaporation will shorten the service life. Significantly decreased.

Therefore, for electric motors such as fan electric motors that are used without replenishment, it is necessary to keep the temperature of the bearing device as low as possible and to design a structure that is easy to cool.

In particular, in an electric motor with an external rotor, the bearing device is located in the center of the stator and has a structure that does not radiate heat directly to the outside air, so a bearing support structure that can shield heat from the stator is required. It is something.

The present invention aims to prolong the life of a small motor with an external rotor as described above, in which the bearing device is subjected to severe thermal conditions, by configuring the stator and the bearing device in an adiabatic manner. We provide bearing devices for small electric motors that are
That is the purpose.

The structure of the bearing device for a small electric motor with an external rotor according to the present invention is such that a cylinder that guides the core and forms a part of the bearing device is placed on the inner circumferential side of a stator core in a small electric motor with an external rotor. A shaped member is provided, and the bearing end portion of the cylindrical member is supported by a support member having a higher thermal resistance than the iron core. An oil-impregnated wick chamber related to the oil storage chamber is formed, and a gap is formed between the support member and the cylindrical member for collecting lubricating oil flowing out from the bearing end into the oil-impregnated wick. This is what I did.

More specifically, in order to firmly support the bearing in a more insulated manner than the stator, a support member made of a support plate made of a thin plate is press-fitted into the stator, and a bearing is fitted to the support member. In short, a gap is formed between the stator and the bearing by the above-mentioned support plate made of steel plate, etc., and this gap is filled with oil-impregnated felt or cellulose fiber. Since it can be equipped with a wick, this gap becomes an oil storage chamber, so it is possible to seal in the lubricating oil necessary for long-term use.

Next, the present invention will be explained based on each illustrated embodiment.

FIG. 1 shows the overall structure of an external rotor type electric motor incorporating an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view taken along line I--I.

In the figure, 1 is a stator, 2 is a rotor, and 3 is a resin.

4 is an iron core of the stator 1, 5 is a winding thereof, 6 is a cylindrical tube that is a cylindrical member, 7 is a bearing, 8 is an oil-impregnated wick, and 9 is a material having a higher thermal resistance than the iron core 4. 10 is the iron core of the rotor 2, 11 is the shaft, 12 is the insert bushing, 13a, 13b are thrust washers, and 14 is a support plate made of a metal plate that is a large support member, such as a thin steel plate. , snap ring, 15 is a fan, 16
is an oil flinger○ In other words, the stator 1 is molded with resin 3,
In addition, the winding 5 is passed through the slot of the iron core 4 of the stator 1.
is arranged, this iron core 4 is guided by a cylindrical tube 6,
Laminated.

On the inner circumferential side of the cylindrical tube 6, support plates 9 are press-fitted into both ends of the bearing 1 in order to firmly support the bearing 7, and the bearing 1 is fitted into the support plate 9. This is what makes up the .

Furthermore, the gap between the bearing 7 and the cylindrical tube 6 is filled with an oil-impregnated wick 8 made of felt or cellulose fiber, and the bearing 7 is an oil-impregnated sintered bearing. consisting of an oil-impregnated wick 8
lubricating oil is supplied by capillary action.

On the other hand, the iron core 10 of the rotor 2 is made of die-cast aluminum, for example, and has an integral ring shape, and the rotor 2 is a so-called external rotor that rotates on the outer circumferential side of the stator 1.

A shaft 11 is press-fitted into the center of the rotor 2 through an insert bushing 12, and the rotor 2 is incorporated into and supported by the above-mentioned bearing device.

In this case, the axial clearance is adjusted by the thrust washer 13a together with the oil flinger 16, and the snap ring 14 is fitted into one end of the shaft 11 after passing through the bearing 7.
It receives shaft thrust through the thrust washer 13b.

The function of the bearing device in the external rotor type electric motor constructed as described above will be described in detail below.

As mentioned above, the gap between the bearing γ and the cylindrical tube 6 is filled with the oil-impregnated wick 8, so it becomes an oil storage chamber, and the bearing T is lubricated without replenishment.

However, in this case, the shape of the support plate 9 made of steel plate is triangular as shown in FIG. It is joined to the cylindrical tube 6 at three locations on the outer periphery, and the above-mentioned gaps are formed at the other locations.

, that is, the case 3 shown in the figure in which the support plate 9 is not connected to the cylindrical tube 6
These gaps are necessary for enclosing the oil-impregnated wick 8, which can be press-filled in an oil-impregnated state like cellulose fibers.
It is nothing but a path necessary for the lubricating oil flowing out from both ends to be absorbed into the oil-impregnated wick 8 again.

As described above, when the shaft 11 rotates, the bearing 7 is lubricated by oozing lubricating oil onto the sliding surface due to the frictional heat of the sliding surface and the action of the rotary pump of the shaft 11. It flows out to both ends of the bearing 7.

On the other hand, the lubricating oil that has flowed out to both ends of the bearing 7 is collected into the oil-impregnated wick 8 through the gap in the support plate 9, and at the same time,
Since lubricating oil is supplied to the bearing 7 from the oil-impregnating wick 8 by capillary action, the lubricating oil is constantly circulated.

However, since the heat generating part of the electric motor is the winding 5, the heat generated by the winding 50 is transmitted to the iron core 4 of the stator 1.

Further, heat is transferred from the iron core 4 to the bearing 7 through the support plate 9 and the oil-impregnated wick 8, which serve as heat passages.

However, the support plate 9 has a large thermal resistance due to its material composition including the formation of a thin plate, and the oil-impregnated wick 8 has poor thermal conductivity, so that heat transfer is small.

On the other hand, since the rotor 2 is constantly cooled, the heat of the bearing γ is transferred to the shaft 11, and as a result, the temperature of the bearing 7 decreases.

Therefore, when the temperature of the bearing 7 decreases, the oil-impregnated wick 8 is cooled because it is in contact with the bearing 7, and the thermal deterioration of the lubricating oil and the amount of evaporation are reduced.

Next, FIG. 3 shows the overall configuration of a rotor-external motor incorporating another embodiment of the present invention, and 45 ports in FIG. 4 are a front view and a longitudinal section of the bearing of the bearing device. A front view,
In the figure, parts with the same symbols as in FIGS. 1 and 2 indicate equivalent parts, and 7A is a bearing having a flange part 17.

That is, what is shown in FIG. 3 is an electric motor comprising a bearing device using a flanged sintered bearing shown in FIG. 4, A-5.

In this embodiment, as is clear from the figure, one end of the bearing 7A of the cylindrical tube 6 is supported by a support plate 9, and the other end is supported by the collar portion 1γ. With this configuration, only one support plate 9 is required for the bearing 7A, and the number of parts can be reduced compared to the previous embodiment. It can be integrally formed by knotting, and does not require any special extra steps for attachment.

Also, with this configuration, the same effects as those of the previous embodiment can be expected.

The shape of the support plate 9 described above is not limited to that shown in each of the above embodiments, and in short, the shape of the support plate 9 is
, 7A, as long as the structure satisfies the need to form a passage through which the lubricating oil flowing out from the end surface of the oil-impregnated wick 8 is collected. It is sufficient to provide at least one gap on the circumference. As explained above, according to the bearing device according to the present invention, the bearing device is located at the center of the stator, and For small rotor-outer rotor type electric motors that require a bearing support structure that does not radiate heat directly to the outside air and can shield heat from the stator, it is possible to achieve the heat shielding effect (heat shielding effect) and also supply a large amount of lubricating oil. In addition, the oil spilled from the end face of the shaft can be recovered, and thus it can be used for a long period of time without replenishing lubricating oil, and can be said to be an invention with excellent practical effects.

1. Brief Description of the Drawings FIG. 1 is a schematic vertical cross-sectional view of a rotor-outer rotor type small electric motor incorporating an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view taken along the line I-I. FIG. 3 is an abbreviated longitudinal sectional view of a rotor-outer rotor type small electric motor incorporating another embodiment, and FIG.

1...Stator, 2...Rotor, 3...
... Resin, 4 ... Iron core, 5 ... Winding wire, 6 ... Cylindrical tube, 7,7A ... Bearing, 8 ... ... Oil-impregnated wick, 9 ... Support plate, 10 ... Iron core, 11 ... Curved shaft, 17 ... Curved flange part.

Claims (1)

[Scope of Claims] 1. A cylindrical member that guides the core and forms a part of a bearing device is provided on the inner circumferential side of a stator core in a small motor with an external rotor, and this cylindrical member The end portion of the bearing is supported by a support member having a higher thermal resistance than the iron core, and an oil-impregnated wick chamber relating to an oil storage chamber is formed between the cylindrical member and the bearing by the support member. , an outer rotor type, characterized in that a space is formed between the support member and the cylindrical member for collecting lubricating oil flowing out from the end of the bearing into an oil-impregnated wick. Bearing device for small electric motor. 2. A bearing device for a small electric motor with an external rotor according to claim 1, which is a cylindrical member with both ends of the bearing supported by supporting members. 3. In claim 1, there is provided a rotation system in which one end of a bearing of a cylindrical member is supported by a support member, and the other end of the bearing is supported by a flange provided on the bearing. Bearing device for small external rotor type electric motor.