Lubricating system for a fan

A lubricating system for a fan (10) includes a lubricant storage space (17) formed at an end portion of the fan for receiving lubricant therein. A lubricant temporary retaining space (145) is defined at the other end portion of the fan for temporarily retaining the lubricant therein. A lubricant returning space (125) communicates the lubricant storage space with the lubricant temporary retaining space for enabling the lubricant to flow from the retaining space to the storage space. The returning space is defined in a tube (12) made of plastic, wherein a bearing (13) is mounted in the tube and a stator (15) is mounted around the tube.

FIELD OF THE INVENTION

The present invention relates generally to a heat dissipating fan, and more particularly to a lubricating system for the heat dissipating fan.

DESCRIPTION OF RELATED ART

A fan includes a fan frame, a tube formed at a middle portion of the frame, a bearing disposed in the tube, and a shaft rotatably mounted to a bearing hole of the bearing. Lubricant oil is filled in the tube to carry out lubrication between the bearing and the shaft.

During operation of the fan, lubricant oil stored at a bottom end of the tube will go up to a top end of the bearing by a pump force activated by a relative rotation of the shaft to the bearing. The oil may escape from the tube from the top end of the bearing. When this happens, a sufficient lubrication cannot be obtained between the shaft and the bearing, and a friction between the shaft and the bearing is increased, which finally may reduce the life term of the fan. So a lubricating system of good oil retaining capability is needed by the fan for satisfying the requirement of the long-term life of the fan.

In order to prevent the oil from leakage from the top end of the bearing, a plurality of oil returning grooves is defined in an outer periphery wall of the bearing for facilitating the oil driven to the top end of the bearing to flow downwardly back to the bottom end thereof. As the oil repeatedly goes up to the top end of the bearing and goes back down to the bottom end of the bearing, a circulating lubrication loop for the shaft and the bearing is formed.

In this lubricating system, the oil returning grooves are formed in the outer periphery wall of the bearing, which causes the manufacture of the bearing to be complicated and accordingly expensive.

In view of the above-mentioned problems of the lubricating system of the fan, there is a need for a lubricating system having good oil retaining capability and low manufacturing cost.

SUMMARY OF INVENTION

The present invention relates to a lubricating system for a fan. According to an embodiment of the present invention, the lubricating system includes a lubricant storage space formed at a bottom end portion of the fan for receiving lubricant therein. A lubricant temporary retaining space is defined at a top end portion of the fan for temporarily retaining the lubricant therein. A lubricant returning space communicates the lubricant storage space with the lubricant temporary retaining space, whereby the lubricant can flow from the retaining space to the storage space via the returning space. The returning space is defined in a tube made of plastic. A bearing is mounted in the tube. A stator is mounted around the tube. A rotor has a shaft which is rotatably fitted in the bearing. The rotor has a hub to which a top of the shaft is secured. The hub has fan blades formed at an outer periphery thereof. The retaining space is defined in an annular wall formed by the hub and surrounding the top end of the shaft of the rotor.

Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a heat dissipating fan10includes a rectangular shaped fan frame11, a hollow tube12integrally formed at a middle portion of the frame11, a bearing13disposed in an inner hole of the tube12, a rotor14rotatably mounted to a bearing hole of the bearing13, and a stator15fixedly disposed around a periphery wall of the tube12. A sealing cover16is hermetically mounted to a bottom end of the tube12for preventing lubricant such as oil from leakage from the bottom end of the tube12. An oil storage space17is defined in the bottom end of the tube12between the sealing cover16and a bottom end of the bearing13for storage of the oil therein.

Referring toFIGS. 3 and 4, the tube12is made of plastic, and includes a tubular first wall121for mounting of the stator15thereon, a second wall122located inside the first wall121and spaced from the first wall121along a radial direction of the tube12, and a ring-like connecting portion123formed between the first wall121and the second wall122for integrally connecting the second wall122to the first wall121at a top end thereof. The tube12defines a holding room124inside the second wall122for receiving the bearing13therein, and an oil returning space125between the first and second walls121,122. The connecting portion123defines therein a plurality of oil returning holes126communicating with the oil returning space125for allowing the oil to flow into the oil returning space125through the oil returning holes126. The tube12also includes a plurality of ribs127in the oil returning space125. The ribs127axially extend from the top end of the tube12towards the bottom end thereof, and radially connect the second wall122to the first wall121to thereby strengthen the second wall122. The ribs127are evenly distributed between the first and second walls121,122, and alternately spaced with the oil returning holes126for dividing the oil returning space125into a plurality of small channels (not labeled) communicating with the oil returning holes126and the oil storage space17. In this embodiment, the connecting portion123is integrally formed with the first and second walls121,122via plastic injection molding.

Referring toFIGS. 5 and 6, the rotor14includes a shaft141rotatably mounted in the bearing hole of the bearing13, a hub142connected with the shaft141at a top end of the shaft141, and a plurality of fan blades143radially extending from an outer periphery of the hub142. The hub142includes an annular wall144disposed around the top end of the shaft141. The top end of the shaft141is located at a central portion of the annular wall144. An oil temporary retaining space145is defined between the shaft141and the annular wall144for temporarily retaining the oil therein. The oil temporary retaining space145is positioned adjacent to and aligned with the connecting portion123of the tube12when the shaft141of the rotor14is mounted into the bearing13. A plurality of oil guiding members146is formed in the oil temporary retaining space145by the hub142, which divide the oil temporary retaining space145into a plurality of small spaces145A for retaining the oil therein. A slantwise guiding surface146A is formed on a side of each of the oil guiding members146facing a corresponding small space145A, for guiding the oil retained in the corresponding small space145A to leave therefrom.

Also referring toFIG. 2, as the fan10is activated, the oil retained in the oil storage space17is driven to flow upwardly towards a top end of the bearing13via a pump force caused by the relative rotation of the shaft141in respect to the bearing13. When the oil is driven upwardly, it flows through a gap between the bearing13and the shaft141to lubricate both of them. Then, the oil is received in the small spaces145A of the oil temporary retaining space145after it reaches the top end of the bearing13. As the small spaces145A of the oil temporary retaining space145are filled with the oil, the oil in the small spaces145A falls down to the connecting portion123via the guiding surfaces146A of the oil guiding members146. Next, the oil flows through the oil returning holes126of the connecting portion123into the channels of the oil returning space125. Finally the oil returns to the oil storage space17from the oil returning space125. Thereafter, the oil is pumped upwards again to the oil temporary retaining space145to repeat the lubrication process.

In the lubrication process of a lubrication system according to the present invention, the oil stored in the oil storage space17goes up to the top end of the bearing13to be retained in the oil temporary retaining space145, and then timely goes back to the oil storage space17via the oil returning space125. Under this design, the oil will not be accumulated at the top end of the bearing13, thereby preventing the oil from leakage from the top end of the bearing13and enabling the fan10to be sufficiently lubricated. In the lubrication system of the fan10according to the present invention, the oil temporary retaining space145is positioned adjacent to and aligned with the connecting portion123. This ensures that the oil is not easily thrown away from the bearing13of the fan10when the oil is guided by the guiding surfaces146A of the oil guiding members146located in the oil temporary retaining space145to fall down on the connecting portion123, thereby ensuring that the fan10has a better oil retaining capability and is well lubricated. The oil returning space125is defined between the integrally formed first and second walls121,122of the tube12, which is formed by plastic injection molding. So the present invention does not need to form a plurality of oil returning grooves in an outer periphery wall of the bearing13, which makes the lubrication system of the fan10in accordance with the present invention have a lower manufacturing cost. The bearing13is made of metal. To form grooves in a metal block is more complicated and expensive than to form channels by plastic injection molding.