Oil-circulating structure for fan

An oil-circulating structure for fan has an oily bearing with a central axis hole for pivoting a fan shaft. An oil-collecting recess trench is formed on the inside wall of the axis hole. The oil-collecting recess trench has a double inner screw shape oil-guiding ditch that is separately formed in clockwise and anti-clockwise direction and forms a plurality of crisscrosses in the oil-collecting recess trench. When the fan rotates, a lubricant in the oil-collecting recess trench is driven by the rotating fan shaft to flow the crisscrosses through the double inner screw shape oil-guiding ditch to circulate in the oil-collecting recess trench so as to achieve an internal-recycle oil-circulating system.

FIELD OF THE INVENTION

The present invention is relating to a bearing lubricating structure for DC fan without bushing, particularly to an oil-circulating structure for fan.

BACKGROUND OF THE INVENTION

Since electronic device generates heat during operating, it will damage easily due to overheat without effective heat-dissipation. It is common to install a DC fan without bushing on electronic device for hest-dissipating. The DC fan without bushing has been well known to equip various bearings like a ball bearing or an oily bearing between fan and fan housing in order to enhance rotation and diminish noise for fan. The oily bearing possesses porous structure made by sintering copper alloy or iron alloy so as to absorb lubricant. However, the lubricant will be pushed to sputter by rotating a fan shaft to contaminate entire fan housing when the fan shaft in the oily bearing rapidly rotates, and the oil-retaining quantity of oily bearing reduces and distributes unevenly. Therefore, when the fan is used for a long time, the lubricating efficiency of bearing becomes bad gradually and noise of bearing becomes loud gradually, even the fan will stop rotating.

A heat-dissipating fan was disclosed in R.O.C. Taiwan Patent No. 471557 entitled “lubricating oil-circulating structure for fan shaft”, which is composed of a housing, a stator and a rotor. A bearing has a bearing body with through holes and a ring portion is extended from one end of the bearing body to form an oil tank. A trench is set on the bearing body to make the released lubricant flow to the trench by passing the through holes then return to the oil tank and the through holes by passing the trench. Since the oil tank is set at the ring portion of the bearing and the trench is set on the bearing body, the lubricant will flow to the ring portion of the bearing and easy to contaminate the housing and oil-retaining quantity of bearing will decrease to weaken lubricating effect. Besides, the oil tank and the trench are the shape of a line easy to result in gathering lubricant at one side only, so that the oil-circulating efficiency of lubricant becomes worse.

SUMMARY

The primary object of the present invention is to provide an oil-circulating structure for fan. An oil-collecting recess trench has a double inner screw shape oil-guiding ditch that includes a left-hand internal thread oil-guiding ditch and a right-hand internal thread oil-guiding ditch. The left-hand internal thread oil-guiding ditch and the right-hand internal thread oil-guiding ditch crisscross in the oil-collecting recess trench to form a plurality of crisscrosses. A lubricant inside an oily bearing up-and-down flows inside the oil-collecting recess trench through the double inner screw shape oil-guiding ditch in order to enhance the internal-recycle oil-circulating efficiency.

The secondary object of the present invention is to provide an oil-circulating structure for fan. An oil-collecting recess trench has a double inner screw shape oil-guiding ditch that includes a left-hand internal thread oil-guiding ditch and a right-hand internal thread oil-guiding ditch. The left-hand internal thread oil-guiding ditch and the right-hand internal thread oil-guiding ditch crisscross in the oil-collecting recess trench to form a plurality of crisscrosses. A lubricant inside an oily bearing distributes over the oil-collecting recess trench by flowing through the double inner screw shape oil-guiding ditch so as to form an internal-recycle oil-circulating system for achieving oil-retaining and leak-proof efficiency without installing oil-retaining ring.

According to the oil-circulating structure of the present invention, an oily bearing is set in a fan housing. The oily bearing has an oil-collecting recess trench and a central axis hole for pivoting a fan shaft. The oil-collecting recess trench has a double inner screw shape oil-guiding ditch that includes a left-hand internal thread oil-guiding ditch and a right-hand internal thread oil-guiding ditch. The left-hand internal thread oil-guiding ditch and the right-hand internal thread oil-guiding ditch crisscross in the oil-collecting recess trench to form a plurality of crisscrosses. A lubricant inside the oily bearing up-and-down flows inside the oil-collecting recess trench through the crisscrosses of the double inner screw shape oil-guiding ditch in order to construct an internal-recycle oil-circulating system.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In relation to the fan oil-circulating structure, referring toFIG. 1, the heat-dissipating fan100comprises a fan housing110, a pivoting base120, a fan hub130, an oily bearing140and stators150. The oily bearing140is set between the fan housing110and the pivoting base120. A central axis hole141is applied for pivoting a fan shaft131of the fan hub130.

Referring toFIGS. 2,3and4, the oily bearing140has a central axis hole141and a hollow oil-collecting recess trench142is formed on the central axis hole141inside wall of the oily bearing140so as to store lubricant in the central axis hole141of the oily bearing140. The oil-collecting recess trench142has a double inner screw shape oil-guiding ditch that includes a left-hand internal thread oil-guiding ditch143(clockwise direction) and a right-hand internal thread oil-guiding ditch144(anti-clockwise direction). The left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144don't touch the fan shaft131when the fan shaft131is pivoted in the central axis hole141. Thus lubricant can fully flow in the left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144. Both the left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144may be square, V-shape, arc-shape or trapezoid, however in this embodiment they are V-shape. The left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144crisscross in the oil-collecting recess trench142to form a plurality of crisscrosses145(showed in FIG.4). Referring toFIG. 5, when the fan shaft131rotates, a lubricant flows through the left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144, in which separates at the crisscrosses145to up-and-down flow and recycle in the oil-collecting recess trench142so as to construct an internal-recycle oil-circulating system.

Referring to FIG.1andFIG. 5, the oily bearing140is set on the pivoting base120of the fan housing110. A stator150like coil, circuit board is set around the pivoting base120for magnetically driving the fan hub130to rotate. When the stator150is powered on to generate electromagnetic induction for driving the fan hub130to rotate, the fan shaft131pivoted to the central axis hole141of the oily bearing140also rotates and pushes the lubricant inside the oil-collecting recess trench142to flow. Referring toFIG. 5, as indicated by arrowhead, the lubricant flows along the left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144and is divided to the left-hand internal thread oil-guiding ditch143and the right-hand internal thread oil-guiding ditch144while flowing to the crisscrosses145, and up-and-down recycles in the oil-collecting recess trench142so as to perform an internal-recycle oil-circulating efficiency. Therefore, the oil-circulating structure for fan has an excellent lubrication with an internal-recycle oil-circulation and achieves an excellent oil-retaining efficiency, and which is unnecessary to install conventional oil-retaining ring between conventional fan shaft and oily bearing.

The above description of embodiments of this invention is intended to be illustrated and not limiting. Other embodiments of this invention will be obvious to those skilled in the art in view of the above disclosure.