JPH0823656A - Electric motor bearing device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a bearing device for an electric motor, which has a small number of parts, is easy to assemble, and has a long life. [Structure] A stator 11 is fixed to the outer periphery of a bearing holder 8 having a shaft insertion portion 14 as a center, and a rotary shaft 7 is rotatably supported by the shaft insertion portion 14 via a sintered oil-impregnated bearing 9.
In the electric motor 3 in which the rotor yoke 12 having the field magnet 13 facing the outer peripheral portion of the stator 11 is fixed to one end side of the electric motor 3, one end of the shaft insertion portion 14 of the bearing holder 8 has an integral closing structure 15. Inside the closed end of the shaft insertion portion 14, a thrust washer 18 having wear resistance and a low friction coefficient is internally provided, and the end portion of the rotary shaft 7 is formed in contact with the thrust washer 18 so as to form a projecting spherical surface 19. The magnetic attraction force acting between the stator 11 and the stator 11 causes the end portion of the rotating shaft 7 to be pressed against the thrust washer 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for an electric motor in which a rotary shaft is rotatably supported by a sintered oil-impregnated bearing fitted to a bearing holder fixed to a support plate or the like.

[0002]

2. Description of the Related Art A bearing device for an electric motor of this type has a conventional structure as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 5-111208 and 4-217838. As shown in FIG. 4, these bearing devices basically include a sintered oil-impregnated bearing 102 fixed to a support plate or the like and fitted in a shaft insertion portion of a cylindrical bearing holder 101 having a shaft insertion portion as a center. The rotary shaft 103 of the electric motor is rotatably supported via the shaft. Both ends of the shaft insertion portion of the bearing holder 101 are open, and the opening portion on the side of attachment to the support plate is sealed by the sealing plate 104. On the inner surface of the sealing plate 104, a thrust receiving plate 105 with which the rotary shaft end abuts is attached.

In the one disclosed in Japanese Patent Laid-Open No. 5-111208, one end of the shaft insertion portion of the bearing holder 101 is sealed by a sealing plate 104, and the other end has a bent portion 106 as shown in FIG. The bent portion 106 and the sintered oil-impregnated bearing 102 are formed.
An oil and fat filling portion 108 is formed by the lid 107 that is brought into close contact with the end surface of the. The resin filling portion 108 is filled with oil and fat, and the resin prevents the impregnated lubricating oil from leaking out of the bearing holder 101. On the other hand, in the one disclosed in Japanese Patent Application Laid-Open No. 4-217838, a pressure release space is formed between the sealing plate 104 and the end surface of the sintered oil-impregnated bearing 102, and the sealing plate 104 has a pressure releasing space. A ventilation hole is provided to connect the pressure space and the outside. Since the pressure release space communicates with the outside through the ventilation hole, the rise of internal pressure during operation is suppressed, and the impregnated lubricating oil is prevented from leaking out.

[0004]

The above-described conventional bearing device for an electric motor requires a sealing plate 104 for sealing one opening end of the bearing holder 101, which requires a large number of parts and is troublesome to assemble. There is a point. There is also a problem that the impregnated lubricating oil actually flows out from a gap between the sealing plate 104 and the bearing holder 101 due to a temperature rise due to rotation during operation.

The present invention has been made in order to solve the above-mentioned conventional problems. The problem is to obtain a bearing device for an electric motor, which has a small number of parts, is easy to assemble, and has a long life. That is to simplify the structure of the bearing device.

[0006]

In order to achieve the above object, the invention of claim 1 integrally closes one end of a shaft insertion portion of a cylindrical bearing holder fixed to a frame and having a shaft insertion portion as a center. A thrust member with wear resistance and a low friction coefficient is installed inside the closed end of the shaft insertion part, and the end of the rotating shaft on the side opposite to the fixed side of the rotor yoke is formed into a projecting spherical surface. A means for setting a magnetic attraction force acting between the field magnet and the stator to act in the direction of pressing the end of the rotary shaft against the thrust member is employed.

In order to achieve the above-mentioned object, the invention of claim 2 is such that the end surface of the sintered oil-impregnated bearing mounted on the shaft insertion part is provided around the closed end in the shaft insertion part of the bearing holder in the means according to claim 1. A means for forming a concave oil sump is used.

In order to achieve the above object, the invention of claim 3 employs a means for integrally molding the bearing holder in the means according to claim 1 or 2 with a resin having oil resistance.

[0009]

According to the first aspect of the present invention, one end of the rotary shaft is a wear-resistant thrust member having a low friction coefficient, which is installed inside the closed end of the shaft insertion portion of the bearing holder, and is used as a field magnet. It is pressed by the magnetic attraction that acts between the stator and the stator, and rotates smoothly with few contact surfaces. Since the closed end of the bearing holder has an integrated closed structure, a sealing plate or the like is not necessary, and there is no gap in which impregnated lubricating oil flows out.

In the means according to claim 2, in addition to the function according to claim 1, the impregnated lubricating oil oozing out to the closed end side in the shaft insertion portion of the bearing holder is successively stored in the concave oil reservoir without leaking out. It will be.

In the means according to claim 3, in addition to the operation according to claim 1 or 2,
Manufacturing of the bearing holder is facilitated and durability is improved.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is a sectional view of a blower as an embodiment of the present invention, and FIG. 2 is a perspective view of the blower. This blower has a cylindrical body frame 1 that forms a ventilation path with open ends.
An electric motor 3 is held by a support plate 2 attached to the motor, and an impeller 4 that rotates in the ventilation passage by the electric motor 3 is provided.
The main body frame 1 is made of resin, and an air passage formed inside thereof is formed in a tapered shape whose inner diameter gradually increases from one end to the other end. The open end on the small diameter side is the suction side, and the open end on the large diameter side is the blowout side.

The support plate 2 is formed of a metal plate, and is composed of a central electric motor holding portion 5 for holding the electric motor 3, and a peripheral portion connected to the electric motor holding portion 5 by several mounting feet.
The main frame 1 is attached to the open end on the large diameter side in a lid shape. At the center of the central electric motor holding portion 5, a cylindrical mounting structure formed by burring is formed inward. Hooking claw 6 that can be elastically deformed by partial cutting and raising in the peripheral part
Are provided inward, and the support plate 2 is attached to the main body frame 1 by fitting the hanging claws 6 from the inside into the fitting holes formed in the main body frame 1. The support plate 2 of this embodiment is made of a substrate material of a metal-based circuit board, and a circuit pattern of a control circuit for the electric motor 3 is formed on the electric motor holding portion 5 on the surface on the ventilation path side, and circuit constituent elements are formed. It is implemented.

The electric motor 3 is arranged on the center line in the ventilation passage. That is, a bearing holder 8 that rotatably holds the rotary shaft 7 is supported in a cantilevered manner on the center line of the ventilation passage in the mounting structure at the center of the electric motor holding portion 5 of the support plate 2. The sintered oil-impregnated bearing 9 in a sleeve state is fitted into the bearing holder 8,
A rotating shaft 7 is rotatably supported at the center. A stator 11 around which a coil 10 is wound is fixed to the outer circumference of the bearing holder 8, and a rotor that rotates outside the stator 11 is formed on the free end side of the rotating shaft 7. The coil end of the coil 10 of the stator 11 is functionally connected to the control circuit formed on the support plate 2 at the end of the inscover.
The rotor of the electric motor 3 is composed of a rotor yoke 12 in which one end side of a cylinder is formed into a frustoconical shape, and a field magnet 13 mounted on the inner surface of the cylindrical portion of the rotor yoke 12. It is fitted on the suction side end. A boss portion of the impeller 4 is fitted to the end of the rotary shaft protruding outside the rotor yoke 12. The boss portion of the impeller 4 is joined to the flat surface portion of the rotor yoke 12 on the back surface and is integrated with the rotor yoke 12 by caulking with a welding portion.

The feature of this embodiment resides in the bearing portion of the electric motor 3. That is, the bearing holder 8 holding the rotating shaft 7 is
One end of the shaft insertion portion 14 into which the sintered oil-impregnated bearing 9 is fitted is closed by an integral closing structure 15 which is integrally formed of a resin such as PBT (polybutylene terephthalate) having oil resistance. A projection 16 is formed at the center of the closed end of the shaft insertion portion 14, and a recess 17 is formed around the projection 16 as an oil reservoir facing the end surface of the sintered oil-impregnated bearing 9 fitted in the shaft insertion portion 14. As shown in FIG. The protrusion 16 in the center of the closed end of the shaft insertion portion 14 is a flat plate formed of a wear-resistant slidable material having a low coefficient of friction, for example, PEEK (polyether / etherketone) or a ketone-based engineering plastic. The thrust washer 18 is installed. This thrust washer 18 is formed by the end face of the sintered oil-impregnated bearing 9 and the projection 1 at the closed end.
Pressed down to 6. Rotor yoke 1 of rotating shaft 7
The end of the magnet 2 opposite to the fixed side is formed into a projecting spherical surface 19 with a finishing accuracy of a surface roughness of 0.7 S or less, and the end of the magnet 2 comes into point contact with the thrust washer 18 and the magnet 1
A magnetic attraction force acting between the stator 3 and the stator 11 causes the end portion of the rotary shaft 7 to move toward the thrust washer 18 regardless of the mounting posture.
It is set to work in the direction of pressing.

For example, in FIG. 1, the impeller 4 is on the lower side,
In the mounting position where the thrust washer 18 is on the upper side,
Impeller 4, rotating shaft 7, rotor yoke 12, magnet 1
The self-weight of the parts such as 3 acts in a direction to reduce the force acting in the direction of pressing the end portion of the rotating shaft 7 against the thrust washer 18, but also in consideration of this, the end portion of the rotating shaft 7 is attached to the thrust washer 18. In order to prevent the force acting in the pressing direction from becoming zero, the relationship between the strength of the magnetic attraction force due to the magnetization and the dead weight of the parts such as the impeller 4, the rotary shaft 7, the rotor yoke 12 and the magnet 13 is set.

The blower having the above-described structure has a blower function by the electric motor 3 which rotates about the rotating shaft 7 by the electromagnetic force between the magnet 13 and the stator 11. During operation of the electric motor 3, the magnetic attraction force between the magnet 13 and the stator 11 always acts as a force in the direction of pressing the rotary shaft 7 against the thrust washer 18, so that the axial movement of the rotary shaft 7 is regulated and smoothed. Rotation is realized. Further, the sliding portion of the rotary shaft 7 with respect to the thrust washer 18 has a projecting spherical surface 19 with a small contact area, and the thrust washer 18 is made of a slidable material having wear resistance and a low friction coefficient. Smooth rotation is possible even under load, and the long service life is overcome by overcoming the low service life due to wear.

The bearing holder 8 is not configured to be closed at one end by a separate component, but is configured to be closed by the integral closing structure 15 by shaving a metal material or integrally molding it with a resin, so that a sealing plate or the like is unnecessary. In addition, since the trouble of assembling such parts is eliminated and there is no gap in the relevant part, the impregnated lubricating oil that has exuded from the sintered oil-impregnated bearing 9 due to the temperature rise does not leak out, and the service life is extended. Will contribute. In particular, in the case where the concave portion 17 is provided as an oil reservoir for accumulating the impregnated lubricating oil that has exuded, the impregnated lubricating oil that has exuded in the concave portion 17 is successively stored, so the leakage of the impregnated lubricating oil is prevented more reliably. In addition, since the impregnated lubricating oil that has been stored can be appropriately supplied to the sintered oil-impregnated bearing 9, the degree of achievement of a long service life is high. The bearing holder 8 and the thrust washer 1 are integrally formed of resin.
8 is lighter in weight, higher in productivity, and lower in cost.

Example 2. In the first embodiment described above, the thrust washer 18 has a thin flat plate shape and is pressed against the protrusion 16 at the closed end of the shaft insertion portion 14 at the end of the sintered oil-impregnated bearing 9, but this embodiment shown in FIG. Thrust member 20 as in 2
By configuring the closed end with the bearing holder 8, it is possible to further simplify the configuration of the relevant portion. That is, as shown in FIG. 3, the closed end side of the shaft insertion portion 14 has a smaller inner diameter than the portion where the sintered oil-impregnated bearing 9 is fitted, and the inner end surface 21 of the closed end is flat. Then, in the shaft insertion portion 14 between the inner end surface 21 and one end of the sintered oil-impregnated bearing 9 fitted,
The thrust member 20 having a frustoconical shape is interposed so that the large diameter side contacts the inner end surface 21. As a result, the closed end of the bearing holder 8 may be closed with a simple shape, and the closed end of the W-shaped cross section having the recess 17 as the oil reservoir as in the first embodiment is formed by the thrust member 20 and the bearing holder 8. The structure is obtained and the same function as that of the first embodiment can be achieved. The other configurations and functions are the same as those of the first embodiment, and therefore their explanations are omitted. In addition, in FIG. 3 related to the second embodiment, the same or corresponding portions as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

[0020]

As is apparent from the above description of the embodiments, according to the first aspect of the invention, one end of the rotary shaft is equipped with wear resistance inside the closed end of the shaft insertion portion of the bearing holder. The thrust member having a low friction coefficient is pressed by the magnetic attraction force acting between the field magnet and the stator, and smoothly rotates with a small contact surface. Since the closed end of the bearing holder has an integrated closed structure, there is no need for a sealing plate, etc., and there is no gap for impregnated lubricating oil to flow out to that part, so the number of parts is small and a long service life is easily achieved even when assembled. A bearing device for an electric motor that can be obtained is obtained.

According to the invention of claim 2, in addition to the effect of claim 1, the impregnated lubricating oil oozing out to the closed end side in the shaft insertion portion of the bearing holder is successively stored in the concave oil reservoir without leaking out. Therefore, the life can be further extended with a simple structure.

According to the invention of claim 3, in addition to the effect according to claim 1 or 2, the manufacture of the bearing holder is facilitated and the durability is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a blower as an embodiment of the present invention.

FIG. 2 is a perspective view of a blower as an embodiment of the present invention.

FIG. 3 is a sectional view of a main part of an electric motor according to a second embodiment.

FIG. 4 is a cross-sectional view of a conventional blower.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body frame 2 Support plate 3 Electric motor 7 Rotating shaft 8 Bearing holder 9 Sintered oil-impregnated bearing 11 Stator 12 Rotor yoke 13 Magnet 14 Shaft insertion part 15 Closure structure 17 Recessed portion 18 Thrust washer 19 Projected spherical surface 20 Thrust member

Claims (3)

[Claims] 1. A stator is fixed to the outer periphery of a cylindrical bearing holder which is fixed to a support plate or the like and has a shaft inserting portion as a center, and a sintered oil-impregnated bearing is interposed in the shaft inserting portion of the bearing holder. In a motor in which a rotating shaft is rotatably supported, and a rotor yoke having a field magnet facing the outer peripheral portion of the stator is fixed to one end side of the rotating shaft, a shaft inserting portion of the bearing holder is provided. One end of the shaft is integrated with a closed structure, and a thrust member having wear resistance and a low coefficient of friction is installed inside the closed end of the shaft insertion part, and the thrust member is opposite to the fixed side of the rotor yoke of the rotary shaft. The end portion on the side is formed in contact with a projecting spherical surface, and the magnetic attraction force acting between the magnet and the stator is set so as to act in the direction of pressing the end portion of the rotating shaft against the thrust member. Characteristic electric motor Bearing device. 2. The bearing device for an electric motor according to claim 1, wherein the bearing holder is provided around a closed end in a shaft insertion portion,
A bearing structure for an electric motor, characterized in that a sintered oil-impregnated bearing mounted on a shaft insertion portion has a concave oil reservoir facing the end surface. 3. The bearing device for an electric motor according to claim 1 or 2, wherein the bearing holder is integrally molded with a resin having oil resistance.