JPH0765618B2 - Bearing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device used in a small motor, and more particularly to a thrust bearing device, and more particularly to a small-sized tape drive source such as a tape recorder or a video tape recorder. It concerns a motor.

2. Description of the Related Art In recent years, needs for light, thin, small, and small compact motors have increased with the expansion of the household and industrial markets, and the development of ultrasmall compact motors has been desired. This motor will be described with reference to FIGS. 3 and 4 as an example of a coreless DC motor.

In FIGS. 3 and 4, reference numeral 5 denotes a shaft having an arcuate tip, which is rotatably supported by a sleeve bearing 9 provided on the frame 11.

A plurality of molded windings 6 and a commutator 7 which are integrally molded by a plastic molding material 8 are attached to the shaft 5 to form a rotor. Reference numeral 12 is a magnet fixed to the frame 11 so as to face the shaping winding 6, 13 is a yoke facing the magnet 12 through the shaping winding 6, 14 is a brush slidingly contacting the commutator 7, and 15 is a frame 11 A thrust bearing 10 for receiving the tip of the shaft 5 is provided at the center of the inner bottom portion of the bracket that covers the end opening of the shaft.

In the above structure, when the shaft 5 is supported by the radial bearing 9 and rotates, a load in the thrust direction is applied to the thrust bearing 10.
It is structured to be received at. At this time, the load received by the thrust bearing 10 is, for example, 10 to 600 gr in the case of a method of applying a thrust load using a magnetic force in order to prevent the rotor from moving up and down, and the load of the shaft having a diameter of 1 to 2 mm. In this case, the diameter of the contact portion of the thrust bearing is about 0.2 mm, and the load per unit area is 0.3 to 20 Kgf / cm ² .
The thrust bearing 10 that receives the load and rotates at a high speed is very easily worn. Therefore, it is conceivable that the thrust bearing 10 is made of a hard material, for example, so-called hard ceramic such as partially stabilized zirconia, silicon carbide, or alumina in order to supplement the wear resistance of the thrust bearing 10. However, when such a hard ceramic is used, the shaft 5 may be worn instead of the bearing 10.
Further, such a hard ceramic has a problem that it is easily cracked by impact. Such cracking due to impact can be solved by increasing the thickness of the ceramic itself, but the needs for lightness, thinness, and smallness cannot be satisfied.

The following table shows examples of materials used in conventional thrust bearings and examples of various characteristics.

The test conditions in the above table are: 1. Test temperature: Room temperature 2. Rotation speed: 2200 rpm 3. Rated output: 0.1W 4. Voltage: 4.2V 5. Current value: 100mA.

As described above, as shown by the results, when hard ceramics are used, problems arise in terms of wear resistance and impact resistance.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to reduce wear due to sliding of a shaft and a thrust bearing of a small motor, and to prevent cracking due to impact and to make the motor lighter, thinner, and smaller. In particular, it is intended to improve performance such as reduction of electric power and reduction of vibration noise when used as a tape drive source of a tape recorder or the like.

Means for Solving the Problems In order to solve the above problems, the present invention provides a bearing plate made of a steel plate, which is composed of a motor case as a thrust bearing, with a soft ceramic coating such as enamel on one or both sides. It was done.

By the above means, neither the shaft nor the bearing is worn against each other, the sliding property of the bearing is improved, and the life of the motor is extended. Further, the bearing plate is made of a motor case, and at least a portion that comes into contact with the tip of the shaft is provided with a soft ceramic, so that it is possible to realize a light, thin, short, and small size.

Embodiment FIG. 1 shows an embodiment of the present invention. The structure other than the thrust bearing is the same as the conventional structure, and the description thereof is omitted. In the figure, 1 is a bearing plate made of a steel plate which also serves as a motor case, and is fired at a temperature at which the shape of the steel plate constituting the bearing plate can be maintained only in the portion of the thrust bearing portion on one side with which the shaft 5 abuts. The ceramic coating 2 is made of soft ceramic. Grease 4 is applied to the sliding surface.

FIG. 2 is useful when the bearing plate 1 made of a steel plate, which also serves as a motor case, has ceramic coatings 2 and 3 applied to both sides of the steel plate and there is a risk of corrosion. The bearing of the present invention does not have a surface hardness significantly different from that of the shaft unlike the conventional ceramic bearing, and the shaft (as an example,
SUS420J with 650 Vickers hardness)
Select 850-950 from 650-750. The surface roughness is 0.1 to 2.0 μm, and grease is applied to the sliding surface.

The material and the coating method of the bearing plate 1 are as follows.

1. Steel plates used as base materials are a) steel plates for enameled b) aluminized steel plates c) SUS steel plates d) other steel plates.

2. Coating methods include a) wet depping method, b) wet spray method, c) dry powder coating method, and d) dry electrostatic coating method.

The following table shows examples of various characteristics of the bearing of the present invention.

The test conditions in the above table are: 1. Test temperature: Room temperature 2. Rotation speed: 2200 rpm 3. Rated output: 0.1W 4. Voltage: 4.2V 5. Current value: 100mA.

The Vickers hardness of each bearing is as follows: Bearing 1: 650 to 750Hv Bearing 2: 750 to 850Hv Bearing 3: 850 to 950Hv.

As an example of the composition of the frit for ceramic coating, the following can be used. Compositions 1 to 3 in the following table
Correspond to the bearings 1 to 3, respectively.

EFFECTS OF THE INVENTION As is apparent from the above description, the present invention has the following effects.

1) Improved wear resistance of the thrust bearing allows smooth rotation and longer life.

2) There is no formation of a recess due to wear of the thrust bearing, and the phenomenon of the rotor moving up and down due to the minute grinding motion of the shaft is eliminated, and a motor with excellent low levels of vibration and noise can be obtained.

3) As a result of 2), wow and flutter can be reduced especially when used in a tape recorder or the like.

4) Since the surface of the thrust bearing is smooth for a long time,
The power consumption can be reduced, and an energy saving type motor can be obtained.

5) Since the ceramic coating is applied to the steel plate as the base, it is possible to obtain a thrust bearing with excellent impact resistance.

6) Since the bearing plate is composed of the motor case and the thin ceramic coating layer is formed, it is possible to obtain a thrust bearing which can contribute to a lighter, thinner, shorter and smaller device.

7) When the steel sheet for ceramic coating is a base that may be corroded, double-sided coating can be performed to obtain a thrust bearing having more corrosion resistance.

8) The surface of the ceramic coating is porous when viewed microscopically, and the grease applied can be retained for a long period of time, contributing to the extension of the life of the thrust bearing.

As a result of the above 1) to 8), the quality of the small motor is improved, the life of the small motor can be greatly extended, and a motor of a light, thin, short and small design can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a motor showing a first embodiment of the present invention,
FIG. 2 is a sectional view of a bearing plate according to another embodiment of the present invention,
FIG. 3 is a sectional view of a conventional motor, and FIG. 4 is a perspective view showing the structure of a general rotor. 1 ... Bearing plate, 2.3 ... Ceramic coating, 5
……shaft.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Saeki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Atsushi Nishino 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshihiro Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References Japanese Patent Publication 25-3981 (JP, B1) Japanese Patent Publication 54-26657 (JP, B2)

Claims (2)

[Claims] 1. A structure in which a bearing plate made of a steel plate for supporting a tip of a shaft is coated with a ceramic coating, the bearing plate is constituted by a motor case, and at least a portion abutting the tip of the shaft is coated with a ceramic coating. The bearing device is characterized in that the coating is made of soft ceramic such as enamel. 2. The bearing device according to claim 1, wherein the bearing plate is composed of a motor case, and both surfaces of the motor case are provided with a ceramic coating.