BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the present device 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 device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is an exploded, isometric view of an electric fan in accordance with a preferred embodiment of the present invention;
FIG. 2 is an assembled, cross sectional view of the electric fan of FIG. 1;
FIG. 3 is an enlarged view of a partition element of the electric fan of FIG. 1;
FIG. 4 is a cross-sectional view taken along line III-III of FIG. 3;
FIG. 5 is an assembled, cross sectional view of an electric fan in accordance with an alternative embodiment of the present invention;
FIG. 6 is an enlarged view of a partition element of the electric fan of FIG. 5; and
FIG. 7 is a cross-sectional view taken along line VI-VI of FIG. 6;
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1-2 illustrate by way of example an electric fan in accordance with a preferred embodiment of the present invention. The fan comprises a fan base 10, a rotor assembly 20, a stator assembly 30, a bearing system having a plain bearing 40 (i.e., sleeve bearing) and a rolling bearing 50 (i.e., ball bearing), and a partition element 60 for separating the plain bearing 40 from the rolling bearing 50. The rotor assembly 20 is pivotable with respect to the stator assembly 30.
The fan base 10 defines a cavity therein for receiving the rotor assembly 20 and the stator assembly 30 therein. A center tube 11 is formed at a center portion of the fan base 10. The center tube 11 has a hollow and cylindrical configuration. The bearing system is engagingly received in the center tube 11, wherein the rolling bearing 50 is located in an upper portion of the center tube 11 and the plain bearing 40 is located in a lower portion of the center tube 11. The partition element 60 is transversely disposed between the rolling bearing 50 and the plain bearing 40, for separating the rolling bearing 50 from the plain bearing 40. The stator assembly 30 is attached around the center tube 11. An annular step 110 is formed on an inner wall of the center tube 11 and is located between the rolling bearing 50 and the plain bearing 40, for supporting the partition element 60 thereon. An annular plate 112 extends from an inner wall of the lower portion of the center tube 11 and engages with a bottom of the plain bearing 40, for supporting the plain bearing 40 thereon. A lubricant reservoir 14 is formed in the fan base 10 below the plain bearing 40, for supplying lubricant oil whilst the fan is operating.
The rotor assembly 20 comprises a generally cup-like fan hub 22 having a top wall (not labeled) and a periphery wall (not labeled). A plurality of fan blades 21 are formed around the periphery wall of the fan hub 22. An axle seat 24 is formed on a center of the top wall. A pivot axle 23 extends perpendicularly downwards from the top wall of the fan hub 22 and is surrounded by the axle seat 24. A semispherical-shaped guiding portion 230 is formed at a distal end of the pivot axle 23. An annular slot 232 is defined in the vicinity of the guiding portion 230 for receiving a ring-shaped retainer 500 (shown in FIG. 2) to prevent the rotor assembly 20 from being thrown out of the fan base 10 under a centrifugal force generated by the pivot axle 23 as the fan is operated. Another annular slot 234 is defined in the pivot axle 23 for receiving the partition element 60. The annular slot 234 is located generally corresponding to the annular step 110 formed on the center tube 11.
The plain bearing 40 has a cylindrical shape, and has a circumferential wall 41. A central hole 42 is defined in a central portion of the plain bearing 40 for receiving the pivot axle 23 therein, whereby the pivot axle 23 rotates with respect to the plain bearing 40. The rolling bearing 50 also has a cylindrical shape and defines a central hole 54 therein. The rolling bearing 50 comprises an inner race 51, an outer race 52, a top and bottom walls (not label) connecting an upper and lower ends of the inner and outer races 51, 52, and a plurality of balls 53 freely rotating between both races 51, 52. The pivot axle 23 extends through the central hole 54 and interferingly engages with the inner race 51 of the rolling bearing 50 to rotate with the inner race 51 of the rolling bearing 50. An elastic ring 70 fits around an upper portion of the pivot axle 23 and is located between a top of the inner race 51 and a bottom of the axle seat 24 of the fan hub 22, preventing vibration of the rolling bearing 50 as the fan operates.
Referring to FIGS. 3-4, the partition element 60 comprises a substantially plate-like body 61 having a central hole 62 defined therein. The partition element 60 is engaged in the annular slot 234 of the pivot axle 23 after the pivot axle 23 extends through the central hole 62, wherein the central hole 62 has a bigger diameter than that of the pivot axle 23 corresponding to the annular slot 234 to prevent a friction between the pivot axle 23 and the partition member 60 as the fan is operated. The body 61 defines four symmetrical elongated slots 610 around and communicating with the central hole 62, for providing elasticity to the body 61 of the partition element 60, whereby the pivot axle 23 can extend through the central hole 62 to reach a position in which an inner edge portion of the body 61 around the central hole 62 extends into the annular slot 234. An annular supporting portion 63 is formed on an outer edge of the body 61 to support the outer race 52 of the rolling bearing 50. The annular supporting portion 63 has a height larger than that of the body 61. Accordingly, the body 61 is separated from the inner race 51 of the rolling bearing 50 (best seen in FIG. 2) so that friction between the inner race 51 and an upper surface of the body 61 is prevented when the electric fan is assembled and operated. Four blocks 630 are symmetrically formed an outer surface of the supporting portion 63 so as to allow their being embedded in corresponding cutouts (not labeled) defined in the center tube 11, thereby preventing rotation of the partition element 60 with the pivot axle 23.
Again referring to FIG. 2, as the fan operates, the pivot axle 23 pivots in the bearing assembly. Under centrifugal force generated by the pivot axle 23, the lubricant oil contained in the lubricant reservoir 14 is drawn upwardly towards a top end of the plain bearing 40 to lubricate the pivot axle 23 and the plain bearing 40. When the lubricant oil is driven upwardly, the lubricant oil flows through at least one gap between the plain bearing 40 and the pivot axle 23 to lubricate both of them. When the lubricant oil reaches the top end of the plain bearing 40 and is blocked by the partition element 60, it flows along the circumferential outer wall of the plain bearing 40 and back to the lubricant reservoir 14. Since the rotor assembly 20 is continuously pivoting, the lubricant oil in the lubricant reservoir 14 is then moved upwardly along the pivot axle 23 by the centrifugal force of the pivot axle 23 to repeat the lubricating process.
In the fan according to the preferred embodiment, the partition element 60 prevents impurities in the lubricant oil from flowing into the rolling bearing 50 with the lubricant oil. The lifetime of the bearing system is thus extended.
Referring to FIGS. 5-7, a fan of an alternative embodiment is similar to that of the first preferred embodiment. However, a partition element 60a replaces the partition element 60 of the previous preferred embodiment. The partition element 60a comprises a plate-like body 61a and an elastic washer 63a mounted on the body 61a. The body 61a is similar to the body 61 of the first preferred embodiment, and defines a central hole 62a therein and four symmetrical elongated slots 610a around the central hole 62a. Four blocks 612a are symmetrically formed an outer surface of body 61a so as to allow their being embedded in corresponding cutouts (not labeled) defined in the center tube 11, thereby preventing rotation of the partition element 60a with the pivot axle 23. The elastic washer 63a is used for supporting the outer race 52 of the rolling bearing 50 and preventing vibration between the rolling bearing 50 and the partition element 60a. The partition element 60a prevents impurities in the lubricant oil from flowing into the rolling bearing 50 with the lubricant oil. The lifetime of the bearing system is thus extended
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Patent Application
20080008590
