Fan and bearing structure

The present invention provides a fan including a stator and a rotor coupled to the stator. The stator has a base and a bearing disposed inside the base. The rotor has a shaft supported by the bearing. Furthermore, the shaft has a concave structure formed on a surface thereof, or the bearing has a groove structure formed on a surface thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 097101494, filed in Taiwan, Republic of China on Jan. 15, 2008, and Patent Application No(s). 097101495, filed in Taiwan, Republic of China on Jan. 15, 2008, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fan, and relates to a bearing structure of the fan.

2. Description of the Prior Art

Fans are usually used in dissipating heats generated by interior electric components during operation all the time. A conventional fan shown inFIG. 1includes a stator and a rotor. The stator includes a base12and a ball bearing14disposed inside the base12. The base12and the ball bearing14support the shaft16of the rotor together. The ball bearing14includes an inner ring and an outer ring rotating relative to each other. The outer ring urges against the base12, and the inner ring urges against the shaft16. Therefore, the cooperation elements must allow certain of deformation to achieve a tight press. However, the deformation causes the variation of the size of the element, and causes a non-uniform stress induced by the element. During the fan operation process, the inner ring of the ball bearing14rotates corresponding to the shaft16so as to generate heat because of the friction, and the heat will enlarge the variation. Additionally, when the shaft is in operation, the size of the shaft varies because of heats, and the abrasion becomes serious, such that the lifetime of the shaft and the ball bearing is lowered. Therefore, after the fan operates in a period of time, the stability of the fan will be lowered by the variation.

SUMMARY OF THE INVENTION

The present invention is to provide a fan and a bearing structure therein.

According to the design of the present invention, a fan includes a stator and a rotor. The stator includes a base and a bearing disposed inside the base. The rotor is coupled to the stator, and includes a shaft supported by the bearing. Therein, a concave structure is formed on a surface of the shaft. The concave structure includes a section plane, an annular concave, a spiral concave, a transversal concave, a longitudinal concave, an oblique concave, a polygonal concave, or a combination thereof.

Additionally, the fan further includes an impeller coupled to an end of the shaft. Therein, multiple airflow-guiding plates are formed on an inner surface of a hub of an impeller. When the impeller rotates, the airflow-guiding plates can guide airflows to pass through the concave structure.

Preferably, the bearing has a top end-surface, a bottom end-surface, and at least one groove structure. The groove structure extends out of the top end-surface or the bottom end-surface to allow airflows to pass through the groove structure.

According to another design of the present invention, the fan includes a stator and a rotor coupled to the stator. The stator includes a base and a bearing disposed inside the base, and a groove structure is formed on a surface of the bearing. The rotor includes a shaft supported by the bearing.

A groove structure is formed on a surface of the bearing. The groove structure can be a spiral groove, an annular groove, a transversal groove, a longitudinal groove, an oblique groove, a polygonal groove, or a combination thereof. The groove structure of the bearing is formed on a surface of an inner ring or a surface of an outer ring. Or, the groove structure is formed on both surfaces of an inner ring and an outer ring of the bearing.

Therefore, compared with the prior art under a condition of the same engagement, there is a smaller contacting area between the shaft and the bearing of the present invention and/or between the bearing and the base of the present invention. Such that, the size variation of the fan caused by the engagement is reduced, the whole structure becomes more stable, and the shaft can rotate smoothly. Further, airflows can be allowed to pass through the groove structure of the bearing to dissipate the heat generated by the fan during operation. According, the size variation of the fan is reduced, and the stability of rotation is kept. Additionally, the airflow-guiding plates disposed around the engagement between the shaft and the impeller can enhance the convection of airflows through the groove structure. Thus, the size variation caused by heat is highly reduced, and the stability of rotation is raised.

The advantage and spirit of the present invention can be understood by the following recitations together with the appended drawings.

DETAILED DESCRIPTION OF THE INVENTION

Please refer toFIG. 2A,FIG. 2Ais a cross-sectional view of the fan1according to the first embodiment of the present invention. The fan1includes a base12, a bearing14, a shaft16, an impeller18, and an electromagnetic element19. The fan1connects to a fixed part2(shown as dotted lines) of a system via the base12.

The base12is used for accommodating the bearing14. The bearing14is a ball bearing and includes an inner ring142, an outer ring144, and multiple balls146disposed between the inner ring142and the outer ring144. The outer ring144of the bearing14urges against the base12. A concave structure is formed on the shaft16, and the concave structure is an annular structure164in this embodiment. The shaft16passes through the inner ring142of the bearing14and urges against the inner ring142. The bearing14thereon defines two opposite surfaces148aand148b, and the annular concave164includes two parts164aand164brespectively protruding out of the aforesaid surfaces148aand148b. Accordingly, airflows can be allowed to pass through the annular concave164, such that the heat generated by the fan1during operation can be dissipated. It should be additionally remarked that the impeller18is coupled to an end of the shaft16, the fan1further includes a magnetic ring182cooperated with the electromagnetic element19to actuate the fan1to rotate. When the fan1rotates, the shaft16rotates with the inner ring142of the bearing14at the same time.

In the second embodiment of the present invention, the concave structure can be an oblique concave164′ as shown inFIG. 2B. In the third embodiment, the concave structure includes one or multiple spiral concave164″ as shown inFIG. 2C.

In the fourth embodiment, the concave structure includes multiple transversal concaves164a′″ and multiple longitudinal concaves164b′″ connected to the transversal concaves164a′″, as shown inFIG. 2D. The aforesaid transverse and longitude are relative to the central axis of the shaft (shown as the dotted line inFIG. 2D). Although the transversal concaves164a′″ are not directly connected to exterior air, the whole concave structure via the engagements of the longitudinal concaves164b′″ can allow airflows to pass through the transversal concaves164a′″ and the longitudinal concaves164b′″. Additionally, the aforesaid annular concave164, the oblique concave164′, and the spiral concave164″ can be combined alternatively and formed on the surface of the shaft16.

Please refer toFIG. 3A,FIG. 3Ais a cross-sectional view of the fan3according to a fifth embodiment of the present invention. Compared with the aforesaid first embodiment, the concave structure includes multiple section-planes364aand multiple concaves364b, and an enlarged schematic illustration of the shaft36of the fan3is shown inFIG. 3B. When the impeller38rotates, the airflow-guiding plates384on the impeller38will guide airflows to pass between the section-plane364aand the bearing34. The schematic path of airflow F is shown as a dotted line with an arrow in theFIG. 3A. The design of the airflow-guiding plates384is shown inFIG. 3C, the airflow-guiding plates384is formed on an inner surface of the cup-shaped hub381of the impeller38, and help guiding airflow F to pass through the concave structure. Therefore, the heat generated by the fan3during operation can be quickly dissipated by the airflow F.

According to the aforesaid embodiments, when the shaft has a concave structure, not only the contacting area between the shaft and the bearing can be reduced, but also the size variation can be reduced. Furthermore, the dissipation is enhanced by the concave structure with a penetration structure, the size variation caused by heat is reduced, and the durability and stability can be raised.

The concave structure of the fan of the present invention is formed on the shaft, and the groove structure can also be formed on the bearing to achieve a purpose of the reduction of the size variation. Further, the dissipation of heat can be enhanced as well.FIG. 4Ais a fan according to the sixth embodiment of the present invention. The sixth embodiment is similar in structure to the first embodiment, and the difference is that the groove structure in the sixth embodiment is formed on the ball bearing54. As shown inFIG. 4B, multiple longitudinal grooves5422(parallel to the extension direction of the shaft) are formed on the inner ring542of the ball bearing54, therefore the contacting area between the ball bearing54and the shaft is reduced. Additionally, the longitudinal grooves5422penetrate through two opposite surfaces5424(a top end-surface and a bottom end-surface) of the ball bearing54. Thereby, when the shaft is engaged to the ball bearing54, the longitudinal groove5422can be formed as a tunnel, and airflows can pass through the tunnel to dissipate the heat generated by the ball bearing54during operation. The path of airflows is shown as a dotted line with an arrow inFIG. 4A.

Of course, the aforesaid longitudinal groove5422can be replaced with the spiral groove or the oblique groove5422′ shown inFIG. 4C. The groove structure can also be a combination of the aforesaid grooves5422and5422′.

Additionally, as shown inFIG. 4D, multiple grooves5422′ and5442can also be formed on the inner ring542and the outer ring544of the ball bearing. Although the grooves5422′ and5442are spiral grooves, the present invention is not limited to this. For example, the groove structure can have two oblique grooves and the two oblique grooves are disconnected and formed as V-shaped. In another example, the groove structure can have four oblique grooves are disconnected and formed as V-shaped, or the groove structure can have at least two spiral grooves. In another example, the groove structure can have a plurality of transversal grooves and longitudinal grooves connected to the transversal grooves.

Because the ball bearing urges against the base of the present invention, there is also a problem of a size variation in the cooperation between the ball bearing and the base. Therefore, the formation of the multiple grooves on the outer ring of the ball bearing of the present invention can reduce the contacting area between the ball bearing and the base, and further to reduce the size variation caused by engagement. Furthermore, the engagement between the ball bearing and the base has less effect on the ball bearing and on the engagement between the bearing and shaft. Similarly, when the grooves5442on the outer ring544penetrate through two opposite surfaces5444of the ball bearing54′, the groove5442also has the same heat-dissipation effect as the groove5422′ on the inner ring542, and it is not described here again.

Although the groove structures penetrating two opposite surfaces of the bearing are mostly described in the aforesaid embodiments, but the present invention is not limited to this. The groove structure of the fan of the present invention can also be a polygonal groove, and the structure can reduce the contacting area between the shaft and the bearing or between the bearing and the base as well. Further, the size variation caused by the engagement can be reduced as well.

As a whole, the shaft and the bearing of the present invention having concave structures and groove structures respectively, such that the contacting area between the shaft and the bearing or between the bearing and the base is reduced. Further, the size variation caused by the engagement is highly reduced, the whole structure is more stable, and the shaft can rotate smoothly. Additionally, airflows can be allowed to pass through the groove structure penetrating two opposite surfaces of the bearing to dissipate heat generated by the fan during operation, such that the size variation is reduced and the stability of the rotation is kept. Finally, the airflow-guiding plates disposed around the engagement between the impeller and the shaft can enhance the convection of airflows through the concave structure, and the size variation caused by heat can be highly reduced to raise the stability of the rotation.