JP2008275115A - Oil-impregnated sintered bearing for fan motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the service life and reduce the friction coefficient of an oil-impregnated sintered bearing for a fan motor and to achieve a long service life and electricity saving of the fan motor. <P>SOLUTION: The fan motor uses a cylindrical housing 2 with one end open and the other end blocked, and a bearing unit comprising an oil-impregnated sintered bearing with its outer periphery fixed to an inner peripheral face 11 of the housing 2, its inner periphery being cylindrical for rotatably supporting a rotary shaft, and its pores impregnated with lubricating oil. Three to nine inner peripheral grooves 12 are formed on the inner peripheral face 11 of the oil-impregnated sintered bearing for the fan motor to be tilted by 5-15° with respect to the axis, in which one end is communicated with an end face and the other end is not communicated with an end face, and the end face on the communicated side of the inner peripheral groove 12 is disposed on the side of a blocked side end face 13 of the housing 2 of the bearing unit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sintered oil-impregnated bearing suitable as a bearing for a fan motor used for cooling motors for various uses, electronic equipment, power supply facilities, and the like.

  The fan motor is mounted on an IC package such as a central processing unit, or is installed on the main body frame of a personal computer or power supply equipment, etc., and introduces outside air by rotating the rotor blades or exhausts air inside the frame. To cool electronic devices. Such a fan motor has a structure in which a motor is fixed to a central portion of a frame-shaped casing, and a rotor blade (fan) is attached to the rotor. FIG. 5 is a schematic longitudinal sectional view of an embodiment of a fan motor. The rotor includes a hub 4 fastened to the rotary shaft 3, a rotary blade 5 formed on the hub 4, and a multipolar magnetized magnet 7 fixed to the inner peripheral side of the hub 4. The casing includes a case 6 in which an air hole 61 is formed, a bearing unit in which the bearing 1 is fixed to the bearing housing 2 fixed in the case 6 from the opening side, and a stator 9 having a coil 8. Is done. The rotor rotating shaft 3 is rotatably supported by a bearing 1 of the casing, and a motor for driving the rotor includes a rotor magnet 7, a casing coil 8, and a stator 9. In such a fan motor, the rotor is driven and rotated by the rotating magnetic field generated by the coil 8 and the stator 9 when the coil 8 is energized and the magnetic field of the multipolar magnetized magnet 7, and formed in the rotor. The rotating blades 5 generate an air flow in a fixed direction, and air is sucked or discharged from the air holes 61.

  Some fan motor bearings having the above structure use sintered oil-impregnated bearings (for example, Patent Document 1). As the sintered oil-impregnated bearings, bronze or iron / bronze-based porous sintered alloys are used. A hydrocarbon synthetic oil or a hydrocarbon synthetic oil impregnated with a synthetic lubricating oil mixed with metal soap as a thickener is used in the pores.

Japanese Patent Laid-Open No. 10-164794

  Such fan motors have been used in an increasing amount as the amount of heat generated due to high functionality of personal computers and game machines in recent years has increased. On the other hand, it is desired to extend the life and power consumption of fan motors. For bearings used in fan motors, it is more important to extend the life and reduce the friction coefficient. Accordingly, an object of the present invention is to provide a bearing having a long life and a low coefficient of friction.

  In order to achieve the above-mentioned long life and low friction, the sintered oil-impregnated bearing for a fan motor of the present invention includes a cylindrical housing having one end opened and the other end closed, and an outer periphery within the housing. In a fan motor using a bearing unit comprising a sintered oil-impregnated bearing fixed to a peripheral surface and having an inner periphery that rotatably supports a rotating shaft and having pores impregnated with lubricating oil, the sintered oil-impregnated bearing described above 3 to 9 inner circumferential grooves that are inclined at 5 to 15 ° with respect to the rotation axis, one end communicates with the end surface, and the other end does not communicate with the end surface are formed on the inner circumferential surface of the inner circumferential surface. The end surface on the side where the cylinders communicate with each other is used as the end surface on the closing side of the bearing unit.

  According to the sintered bearing for a fan motor of the present invention, the lubricating oil can be prevented from leaking and the sliding surface can be lubricated well. It can be extended and the coefficient of friction can be reduced, contributing to longer fan motor life and power saving.

  Hereinafter, an embodiment of a sintered oil-impregnated bearing for a fan motor of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a sintered oil-impregnated bearing for a fan motor. FIG. 1A is an end side view of the bearing 1, FIG. 1B is a longitudinal sectional view of the bearing 1, and FIG. 3 is a closed side end view of the bearing 1. FIG. 2 is a longitudinal sectional view of a bearing unit using the fan motor sintered oil-impregnated bearing 1 of FIG. 1, and FIG. 3 is a development view of the inner peripheral surface of the fan motor sintered oil-impregnated bearing 1 of FIG.

The fan motor bearing of the present invention is made of a sintered alloy, and the pores thereof are impregnated with a lubricating oil such as a hydrocarbon-based synthetic oil or a synthetic lubricating oil in which metal soap is mixed as a thickener with a hydrocarbon-based synthetic oil. Has been.
Generally, fan motor bearings having an inner diameter of about 1.5 to 3.5 mm and an axial length of about 5 to 15 mm are used.

  Further, as shown in FIG. 1B, an inner peripheral groove 12 is formed on the inner peripheral surface 11 of the bearing 1, and this inclined inner peripheral groove is one end surface 13 (lower end surface in the figure). And is not in communication with the other end surface 14 (the upper end surface in the figure). As shown in FIG. 2, the fan motor bearing is fixed by being press-fitted or adhered to the inner peripheral surface of the housing 2 having one end opened and the other end closed. At this time, the end face 13 (the lower end face in the figure) on the side where the inner peripheral groove communicates is arranged on the end face fixed to the housing 2 and closed, and the inner peripheral groove communicates with the opening side of the housing. The end face 14 on the side not to be disposed (the end face on the upper side in the figure) is arranged.

  The inner circumferential groove 12 functions as an oil reservoir and has an action of supplying lubricating oil to the inner circumferential surface 11 (sliding surface). Further, as shown in FIG. 3, the inner circumferential groove 12 has a side where the inner circumferential groove 12 communicates with the rotation direction of the shaft 3 (closed side end surface 13) to a side where the inner circumferential groove does not communicate (open side end surface 14). It is an inclined groove toward The sintered oil-impregnated bearing for a fan motor according to the present invention has a configuration in which the inner circumferential groove 12 is inclined as described above, communicated with the closing side end surface 13, and not communicated with the open side end surface 14. (2) The lubricating oil is transferred along the inner peripheral groove 12 to the closing side end surface 13 to increase the hydraulic pressure of the closing side end surface 13. To increase the strength of the oil film supplied to the inner peripheral surface 11 and (3) the lubricating oil is transferred along the inner peripheral groove 12 to the closing side end surface 13 to open the end surface 14 of the sintered oil impregnated bearing. It is possible to prevent the leakage of the lubricating oil from the oil and to suppress the reduction of the life due to the consumption of the lubricating oil. In order to make the effects (1) to (3) effective, the width of the inner circumferential groove 12 is preferably about 0.2 to 1.5 mm. However, FIG. 3 shows an enlarged width of the inner circumferential groove.

  If the inclination angle θ of the inner circumferential groove 12 with respect to the axial direction of the bearing 1 is less than 5 °, the operations (1) to (3) cannot be obtained sufficiently. On the other hand, when the inclination angle θ exceeds 15 °, the axial length l of the oil sump becomes large, but the lubricating oil easily escapes along the inner circumferential groove 12 to the closing side end surface 13, and as a result, the inner circumferential surface. The supply action of the lubricating oil to 11 will be reduced. Therefore, the inclination angle θ of the inner circumferential groove 12 is preferably 5 to 15 ° with respect to the axis.

  Even if the inclination angle θ of the inner circumferential groove 12 is set as described above, if the inner circumferential groove 12 communicates with the opening-side end surface 14, the lubricating oil expands due to the heat generated by the rotation of the shaft, and lubricates from the opening-side end surface 14. Oil leakage is likely to occur, and the life of the bearing is reduced. For this reason, the inner peripheral groove 12 needs to be structured so as not to communicate with the open end surface 14. From this point of view, in the fan motor bearing of the above general size, the distance d between the inner peripheral groove end portion 15 on the side not communicating with the end surface and the bearing end surface 14 on the side where the inner peripheral groove does not communicate is 0.5 mm. It is preferable to hold above. On the other hand, if the distance d between the inner circumferential groove end 15 on the side not communicating with the end surface and the bearing end surface 14 on the side not communicating with the inner circumferential groove becomes excessive, the lubricating action on the sliding surface (1) above on the bearing inner circumferential surface. Therefore, the distance d is preferably in a range not exceeding 2 mm.

  If the number of the inner circumferential grooves 12 is small, the above-described action becomes poor. Therefore, in order to exert the action on the entire inner circumferential surface 11 of the bearing, it is necessary to form three or more. On the other hand, if the number of inner circumferential grooves 12 is too large, the area of the sliding surface decreases and the surface pressure received by the sliding surface increases, so the upper limit is nine.

  In the sintered oil-impregnated bearing for a fan motor having the above-described configuration, when the material density of the inner peripheral surface 11 (sliding surface) is increased, the lubricating oil supplied from the inner peripheral groove 12 becomes the pores of the sintered oil-impregnated bearing. Through this, the lubricating oil pressure becomes high and the oil film of the lubricating oil becomes strong. On the other hand, if the density of the inner circumferential groove 12 is also increased, the lubricating oil circulating function of the original sintered oil-impregnated bearing is impaired. From these viewpoints, the porosity of the inner peripheral surface 11 is preferably 5 to 28%, and the porosity of the groove surface of the inner peripheral groove 12 is preferably 30 to 45%. In order to achieve such a porosity configuration, when preparing a sintered body material of a sintered oil-impregnated bearing having an inner circumferential groove having a porosity of 30 to 45%, and performing recompression such as sizing A desired bearing can be obtained by plastically deforming the inner peripheral surface using a cylindrical core rod, crushing the pores, and adjusting the porosity that opens to the surface of the inner peripheral surface to 5 to 28%.

  In the sintered oil impregnated bearing for a fan motor of the present invention, as shown in FIG. 4, the side end face 13 communicating with the inner circumferential groove 12 is further inclined from the outer diameter side to the inner diameter side in the rotational direction of the shaft 3. In addition, it is preferable to form the end face groove 16 whose end portion communicates with the inner circumferential groove 12. When the end face groove 16 is formed on the bearing closing side end face 13 as described above, the lubricating oil stored in the space formed by the housing 2 and the bearing closing end face 13 is drawn in by the end face groove 16 as the shaft 3 rotates. Then, the drawn lubricating oil can be supplied to the inner circumferential groove 12 to enhance the lubricating oil transfer action (2). The end surface grooves 16 may be formed in the same number as the inner circumferential grooves 12, but may be smaller than the inner circumferential grooves 12.

A raw material powder prepared by adding 45% by mass of electrolytic copper powder, 5% by mass of foil-like copper powder, and 3% by mass of tin powder to iron powder and filling it into a mold is compression-molded. A substantially cylindrical bearing-shaped molded body having a diameter of 5 mm, an inner diameter of 2.5 mm, and a height of 10 mm was obtained. As shown in Table 1, six inner circumferential grooves 12 having different inclination angles were formed.
The inner circumferential groove has a width of 0.5 mm, communicates with one end surface 13, does not communicate with the other end surface 14, and the distance between the end 15 of the inner circumferential groove and the end surface 14 with which the inner circumferential groove does not communicate Was formed to be 1 mm. For comparison, an inner peripheral groove communicated with both end surfaces was also prepared. The density ratio of these molded bodies was adjusted to be 70%. After sintering these molded bodies in an ammonia decomposition gas atmosphere at 780 ° C., the inner peripheral surface was recompressed so that the porosity of the inner peripheral surface was 10%. The porosity of the groove surface of the inner peripheral groove was 38%.
The obtained sample was impregnated with a synthetic lubricating oil (trade name Foil 972P-68, manufactured by Kanto Kasei Co., Ltd.) mainly composed of polyalphaolefin having a viscosity equivalent to ISO VG68 to prepare a bearing sample.
As shown in FIG. 2, the obtained bearing sample was press-fitted into a housing having one end opened so that the end surface communicating with the inner circumferential groove faces the housing bottom, and Examples 1 to 1 shown in Table 1 were obtained. 3 and Comparative Example 1-4 bearing unit samples were prepared. Insert a shaft made of JIS S45C equivalent material with an outer diameter of 2.5 mm into the above bearing unit sample, rotate the shaft at an environmental temperature of 80 ° C. at a rotational speed of 5000 rpm, measure the friction coefficient, After 200 hours of operation of the shaft, the weight of the bearing unit sample was measured, and the oil consumption rate of the lubricating oil from the bearing end surface was measured. These results are also shown in Table 1. Note that the inclination angle θ of the inclined groove in Table 1 is an inclination angle with respect to the axis. In the sample of 0 ° of Comparative Example 1, the inner peripheral groove is formed in parallel to the axial direction, and the inner peripheral groove is not inclined. This is an example. In Comparative Example 4, the inner peripheral groove communicates with both end faces.

  From Table 1, compared to Comparative Examples 1 and 2 in which the inclination angle of the inner circumferential groove is less than 5 ° and Comparative Example 3 in which the inclination angle exceeds 15 °, Examples 1 to 5 having an inclination angle of 5 ° to 15 °. No. 3 has a low friction coefficient, and it was confirmed that good sliding characteristics were exhibited within this range. In Comparative Example 4, the amount of leakage of the lubricating oil is larger than in Examples 1 to 3, and the friction coefficient is also large. From this, it can be seen that it is important that the inner circumferential groove is configured not to communicate with the opening end face of the housing.

  The sintered oil-impregnated bearing for a fan motor of the present invention is suitable for a fan motor, and if used for a fan motor, it can contribute to improvement of durability and reliability of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of one embodiment of the fan motor bearing which concerns on this invention, (a) is a top view of the open side end surface of a bearing, (b) is a longitudinal cross-sectional view of a bearing, (c) is the obstruction | occlusion side end surface of a bearing. FIG. It is a longitudinal cross-sectional view of one embodiment of the bearing unit according to the present invention. FIG. 2 is a development view of the inner peripheral surface of the bearing shown in FIG. 1 which is an embodiment of the fan motor bearing according to the present invention. It is another embodiment of the fan motor bearing according to the present invention, and is a bottom view of the bearing in which the end surface groove is formed on the end surface on the side where the inner peripheral groove communicates. Schematic diagram of the closed end face of It is a longitudinal cross-sectional view of an example of a fan motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bearing 11 Bearing inner peripheral surface 12 Inner peripheral groove 13 Closure side end surface 14 Open side end surface 15 Inner peripheral groove end portion 16 End surface groove 2 Bearing housing 3 Rotating shaft 4 Hub 5 Rotating blade (fan)
6 Case 61 Air hole 7 Magnet 8 Coil 9 Stator

Claims (4)

A cylindrical housing with one end open and the other end closed;
In a fan motor using a bearing unit comprising a sintered oil-impregnated bearing in which the outer periphery is fixed to the inner peripheral surface of the housing, the inner periphery is a cylindrical shape that rotatably supports the rotating shaft, and the pores are impregnated with lubricating oil.
The inner peripheral surface of the sintered oil-impregnated bearing is inclined by 5 to 15 ° with respect to the shaft, and has three to nine inner peripheral grooves each having one end communicating with the end surface and the other end not communicating with the end surface. A sintered oil-impregnated bearing for a fan motor, characterized in that an end surface on the side where the circumferential groove communicates is disposed on the closed end surface side of the housing of the bearing unit.   2. The fan motor according to claim 1, wherein a distance between an end portion of the inner circumferential groove on the side not communicating with the end surface and a bearing end surface on the side where the inner circumferential groove does not communicate is 0.5 to 2 mm. Sintered oil-impregnated bearing.   The sintered oil impregnation for a fan motor according to claim 1 or 2, wherein the porosity of the inner peripheral surface of the bearing is 5 to 28%, and the porosity of the groove surface of the inner peripheral groove is 30 to 45%. bearing. The number of the inner peripheral grooves of the bearing is equal to or less than the number of the inner peripheral grooves, and the bearing is inclined from the outer diameter side to the inner diameter side in the rotation direction of the shaft. The sintered oil-impregnated bearing for a fan motor according to any one of claims 1 to 3, wherein an end face groove communicating with the groove is formed.

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