Ceramic spindle coupling structure

A ceramic spindle coupling structure includes a metal bushing which has a housing space that has an inlet and a tapered fastening section of a smaller diameter than the inlet to form a tight coupling with a ceramic spindle without embossing the ceramic spindle and the metal bushing.

FIELD OF THE INVENTION

The present invention relates to a ceramic spindle coupling structure and particularly to a structure for coupling a ceramic spindle with air fan vanes through a metal bushing.

BACKGROUND OF THE INVENTION

The conventional air fans used on high speed processors such as microprocessors that include metal spindles encounter many problems such as the airflow is not sufficient to disperse the growing amount of heat being generated, rotation speed is not fast enough, etc. Increasing the speed and airflow volume will result in shorter service life of the metal spindle. Therefore ceramic spindle has gradually replaced the metal spindle these days. The ceramic material is very hard and rigid, and can withstand wearing and high temperature. Thus the air fan rotation speed may increase to disperse heat as desired.

However, test process during fabrication shows that there are still problems in the design of the ceramic spindle remained to be resolved. For instance, the ceramic spindle is usually jointly formed with the fan by injection. The ceramic spindle generally has a smooth surface and a low friction coefficient, hence the centrifugal force occurred at high speed rotation of the fan tend to result in separation of the ceramic spindle from the air fan and incurs skid. To remedy this problem, one of the approaches is to increase the friction of the surface of the ceramic spindle so that it can be coupled with the air fan tightly during injection forming. The original purpose of using the ceramic spindle is to take the advantage of its greater hardness and rigidity. The embossing process is useless for the ceramic spindle since the ceramic spindle is very hard and rigid. Even if the embossing process is finally done and successfully created a rough surface to the ceramic spindle, it would be a very time and cost consuming which is not economical.

To solve the aforesaid problem, Applicant has disclosed a patent in ROC patent publication No. 517784 entitled “Ceramic spindle coupling structure for air fans”. In that patent, the ceramic spindle has one end coupled with a metal bushing having a greater friction coefficient. Referring to FIG. 2 of the above patent for an embodiment, the inner ring surface of the metal bushing is embossed by a machine to increase the friction coefficient. The outer surface of the metal bushing is embossed to increase the friction coefficient. Then the metal bushing is tightly coupled with the ceramic spindle. The metal bushing is coupled with the air fan by injection forming to become integrated. Hence the ceramic spindle may be tightly coupled with the air fan without breaking loose. Such a structure requires embossing on the inner ring surface and outer surface of the metal bushing by machining. It needs additional embossing operations for the metal bushing during fabrication process. Production cost is higher. There is still room for improvement.

SUMMARY OF THE INVENTION

Therefore the primary object of the invention is to provide a simpler ceramic spindle coupling structure. A metal bushing with a tapered housing space is provided to form a tight coupling with a ceramic spindle so that embossing of the inner wall and outer surface of the metal bushing to increase the friction force is not necessary. Thereby cost may be reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer toFIGS. 1,2and3, according to the invention an air fan10includes a ceramic spindle11and vanes12. In order to increase the speed and airflow volume of the air fan10, the ceramic spindle11is made from material that is hard and rigid, and can withstand wearing and high temperature. The ceramic spindle11generally has a hard and smooth surface. Hence a metal bushing20is provided as the fastening medium to couple the ceramic spindle11with the vanes12.

Referring toFIGS. 1 and 2, the metal bushing20has a housing space21in the interior. The housing space21has an inlet22and a fastening section23. The housing space21is tapered at the fastening section23from the inlet22so that the ceramic spindle11may be inserted from the inlet22and squeezed and held tightly at the fastening section23to form a secured coupling. The metal bushing20further has a coupling section24at one end corresponding to the inlet22. The coupling section24may be engaged with bores14formed on a connecting section13of the vanes12. Then the connecting section13and the coupling section24are filled and embedded together during injection forming to form a tight coupling. The ceramic spindle11rotates causing the coupling section24to drive the vanes12through the connecting section13without generating relative rotation therebetween. Thereby the ceramic spindle11may be coupled with the vanes12through the metal bushing20.

Referring toFIGS. 2 and 3, for assembly, insert the ceramic spindle11into the housing space21of the metal bushing20through the inlet22until reaching the tapered fastening section23to be squeezed and coupled tightly. As the metal bushing20has a thin wall, it will be slightly expanded by the inserting ceramic spindle11to form a tight coupling without cracking.