1. Field of the Invention
The present invention relates to a cooling fan, and more particularly relates to a cooling fan which can be assembled easily. The present invention relates also to a method for making the cooling fan.
2. Description of Related Art
With the continuing development of the electronic technology, electronic packages such as CPUs (central processing units) are generating more and more heat that requires immediate dissipation. Cooling fans are commonly used in combination with heat sinks for cooling CPUs.
A conventional cooling fan includes a rotor having a shaft extending downwardly from a central portion of the rotor, a bearing defining an inner hole for receiving the shaft therein, and a frame. A central tube extends upwardly from a middle portion of the frame and defines a through hole therein. The bearing is mounted in the through hole of the central tube of the frame. To avoid swinging of the bearing, the bearing is fixedly assembled to the central tube by interferential fitting. However, as the frame is generally made of plastic, when the bearing is placed into the central tube, an inner circumferential periphery of the frame may easily wear out. Thus a clearance may be formed between the bearing and the central tube when the bearing is assembled with the central tube of the frame to form the cooling fan, which, in most of cases, results in instability of the bearing and unbalanced rotation of the rotor of the cooling fan. Thus not only assembly of the bearing is inconvenience, but also results in noise or malfunctioning of the cooling fan. The performance of the cooling fan is reduced, and the life-span is resultingly shortened.
What is needed, therefore, is a cooling fan which can reduce or eliminate lubricant oil loss.
The present invention relates, in one aspect, to a cooling fan. The cooling fan includes a fan housing having a central tube extending upwardly therefrom, a bearing defining a bearing hole therein, a stator mounted around the central tube, and a rotor including a hub having a shaft extending from the hub into the bearing hole of the bearing. The bearing is received and fixedly connected to the central tube during the process of molding the fan housing; thus the bearing and the central tube are integrally connected together during injection molding of the fan housing.
The present invention relates, in another aspect, to a method for making the cooling fan. The method includes steps of: a) providing a bearing; b) mounting the bearing in a mold used for making a fan housing; c) molding the fan housing using injection molding, a central tube being formed fixedly connected to the bearing and around the bearing during the process of molding the fan housing; d) mounting a stator around the central tube; e) mounting a rotor to the bearing.
Other advantages and novel features of the present invention will be drawn from the following detailed description of the preferred embodiments of the present invention with attached drawings, in which:
Many aspects of the present cooling fan can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present cooling fan. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
The housing 10 includes a ring shaped main body 12 defining an aperture (not labeled) in a central portion thereof, a base 14 being formed in the aperture of the housing 10, and a plurality of ribs 13 interconnecting an outer periphery of the base 14 and an inner periphery of the main body 12. The base 14 defines a concave 142 in a central portion thereof. A central tube 15 extends upwardly from the base 14 from a central area of the concave 142. An ear 151 extends radially and outwardly from an outer surface of the central tube 15. The ear 151 has a shape of square column which has a square shaped cross section. Alternatively, the ear 151 can be a semicircular column with a semicircular shaped cross section. An annular flange 152 extends radially and inwardly from an inner surface of a bottom end of the central tube 15. The ear 151 and the flange 152 are integrally formed with the central tube 15 of the housing 10.
The stator 30 is mounted on the central tube 15. The stator 30 includes a stator core 33 consisting of layered yokes, stator coils 34 wound on the stator core 33 to establish an alternating magnetic field, and a PCB 31 (printed circuit board) electrically connected with the stator coils 34. To avoid the coils 34 from coming into electrical contact with the stator core 33, upper and lower insulating frames 32a, 32b are used to cover the stator core 33 and electrically insulate the stator coils 34 from the stator core 33. The PCB 31 defines a mounting hole 310 for extension of the central tube 15 therethrough. A cutout 312 is defined in an inner circumference of the PCB 31 corresponding to a configuration and a position of the ear 151 of the central tube 15. When the stator 30 is mounted on the central tube 15, the ear 151 of the central tube 15 engages with the cutout 312 of the PCB 31 to fix the PCB 31 to the central tube 15.
Also referring to
The bearing 20 is mounted in the central tube 15. The bearing 20 defines a bearing hole 22 therein for extension of the shaft 45 therethrough. The bearing 20 is U-shaped with a bottom end closed and a top end open. A counter plate 26 made of high abrasion-resistant material is arranged in the bottom end of the bearing 20. When the shaft 45 is mounted into the bearing hole 22, the counter plate 26 faces and supportively engages a free end of the rotary shaft 45. The bearing 20 defines an end opening 25 at the top end thereof. The end opening 25 has a diameter larger than that of the bearing hole 22. An oil-retaining cover 28 is mounted in the end opening 25 of the bearing 20. The cover 28 having an upper portion 281 with an inner diameter approximately the same as a diameter of the shaft 45, and a lower portion 282 with an inner diameter larger than the diameter of the shaft 45. When assembled the upper portion 281 of the cover 28 is mounted around the shaft 45 with a position higher than the slot 43 of the shaft 45, and the lower portion 282 of the cover 28 is arranged on the top end of the bearing 20. An oil-retaining space 29 is thus formed between the shaft 45, the top end of the bearing 20 and the cover 28. A ventilating path 24 extends through the bearing 20 along an axial direction thereof. The ventilating path 24 is offset from the axis of the bearing 20 and communicates a bottom of the bearing hole 22 with an exterior of the bearing 20. When the shaft 45 of the rotor 40 is mounted in the bearing hole 22, air in the bearing hole 22 is able to escape along the ventilating path 24 to the exterior of the bearing 20.
Referring to
In the upper half 211 of the bearing pattern 21, every three adjacent first branches, i.e., two first branches 214a of the first grooves 214 plus one intermediate first branch 215a of the second groove 215, or two first branches 215a of the second grooves 215 plus one intermediate first branch 214a of the first groove 214, co-operatively form a Z-shaped groove. In the lower half 212 of the bearing pattern 21, every three adjacent second branches, i.e., two second branches 214b of the first grooves 214 plus one intermediate second branch 215b of the second groove 215, or two second branches 215b of the second grooves 215 plus one intermediate second branch 214b of the first groove 214, co-operatively form a Z-shaped groove. Two groups of continuous Z-shaped grooves are thereby symmetrically formed respectively at upper and lower halves 211, 212 of the bearing pattern 21. The two groups of Z-shaped grooves intersect at the centerline 210 of the bearing pattern 21. By this arrangement, each groove of the bearing pattern 21 is in communication with one of its neighboring grooves, i.e., one first groove 214 and one neighboring second groove 215, are in communication with each other, either at the inner communication ends 213 or at the outer communication ends 218.
As shown in
It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present example and embodiment are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.
Number | Date | Country | Kind |
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200710073465.X | Mar 2007 | CN | national |