1. Field of the Invention
The present invention relates to an impeller. In particular, the present invention relates to an impeller for an axial-flow heat-dissipating fan.
2. Description of Related Art
A complex impeller consisting of two hub parts have been disclosed in, e.g., U.S. Pat. Nos. 6,318,964 and 6,572,336. As illustrated in
As illustrated in
An object of the present invention is to provide an impeller for an axial-flow heat-dissipating fan for increasing the air inlet amount driven by the impeller.
Another object of the present invention is to provide an impeller for an axial-flow heat-dissipating fan with lowered blowing noise. SUMMARY OF THE INVENTION
An impeller for an axial-flow heat-dissipating fan in accordance with the present invention comprises a hub including an outer periphery and a plurality of blades symmetrically formed on the outer periphery of the hub and extending in an inclined angle with respect to a longitudinal direction parallel to a rotational axis of the hub. Each blade includes a leading edge, a trailing edge, a radial inner edge, and a radial outer edge. Two of the blades adjacent to each other overlap with each other in the longitudinal direction such that each blade has a first overlapped area and a second overlapped area.
The first overlapped area on each blade extends outward from the leading edge and the radial inner edge but spaced from the radial outer edge of the blade. The second overlapped area on each blade extend outward from the trailing edge and the radial inner edge but spaced from the radial outer edge of the blade. The air inlet amount is increased and blowing noise is lowered.
The trailing edge of each blade projects on an adjacent blade along a rear projection line. The first longitudinal overlapped area is defined by the rear projection line, the leading edge of the adjacent blade, and the radial inner edge of the adjacent blade.
The leading edge of each blade intersects the radial inner edge of the blade at a front base point. The rear projection line intersects the leading edge of the adjacent blade at a first overlapped point. A distance between the front base point and the overlapped point is ⅕-⅘ of a length of the leading edge.
The rear projection line intersects the radial inner edge of the adjacent blade at a second overlapped point. A distance between the front base point and the overlapped point is ⅙-⅚ of a length of the radial inner edge.
The trailing edge of each blade projects on an adjacent blade along a front projection line. The second longitudinal overlapped area is defined by the front projection line, the leading edge of the adjacent blade, and the radial inner edge of the adjacent blade. The trailing edge of each blade intersects the radial inner edge of the blade at a rear base point. The front projection line intersects the trailing edge of the adjacent blade at a third overlapped point. A distance between the rear base point and the overlapped point is ⅕-⅘ of a length of the trailing edge. The front projection line intersects the trailing edge of the adjacent blade at a fourth overlapped point. A distance between the rear base point and the overlapped point is ⅙-⅚ of a length of the trailing edge.
Preferably, the leading edge of each blade is at an angle between 10 degrees and 90 degrees with the trailing edge of an adjacent blade when viewed from the longitudinal direction parallel to the rotational axis of the hub.
The leading edge of each blade intersects the radial outer edge of the blade at a front end point. The trailing edge of each blade intersects the radial outer edge of the blade at a rear end point. Preferably, a line passing through the front end point of the leading edge and the rear end point of the trailing edge of each blade is at an angle between 10 degrees and 70 degrees with a plane orthogonal to the rotational axis of the hub.
Other objects, advantages and novel features of this invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Referring to
The blades 42 are symmetrically formed on an outer periphery of the hub 41 and extend in an inclined angle with respect to a longitudinal direction parallel to an extending direction of the shaft 40 (i.e., the rotational axis of the hub 41). Each blade 42 includes a leading edge 421 on an air inlet side of the blade 42, a trailing edge 422 on an air outlet side of the blade 42, a radial inner edge 423 on the outer periphery of the hub 41, and a radial outer edge 424 distal to the outer periphery of the hub 41. The leading edge 421, the trailing edge 422, the radial inner edge 423, and the radial outer edge 24 are rectilinear or curved with an appropriate radius of curvature according to product needs. For each blade 42, the leading edge 421 intersects the radial inner edge 423 at a front base point 11, the leading edge 421 intersects the radial outer edge 424 at a front end point 12, the trailing edge 424 intersects the radial inner edge 423 at a rear base point O1, and the trailing edge 424 intersects the radial outer edge 424 at a rear end point O2, best shown in
Still referring to
The distance between the front base point I1 and the first overlapped point P1 is preferably ⅕-⅘ (most preferably ½) of a length of the leading edge 421. Further, the distance between the front base point 11 and the second overlapped point P2 is preferably ⅙-⅚ (most preferably ½) of a length of the radial inner edge 423.
Still referring to
The distance between the rear base point O1 and the third overlapped point P3 is preferably ⅕-⅘ (most preferably ½) of a length of the trailing edge 422. Further, the distance between the rear base point O1 and the fourth overlapped point P4 is preferably ⅙-⅚ (most preferably ½) of a length of the radial inner edge 423.
Referring to
The angle θ1 is preferably between 10 degrees and 90 degrees, and most preferably 45 degrees. Further, the rear projection line L1 on each blade 42 is at the same angle θ1 with the front projection line L2 on an adjacent blade 42. Further, the first overlapped area A1 and the second overlapped area A2 are spaced from the radial outer edge 422 of each blade 42.
Referring to
Referring to
Referring to
While the principles of this invention have been disclosed in connection with a specific embodiment, it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention, and that any modification and variation without departing the spirit of the invention is intended to be covered by the scope of this invention defined only by the appended claims.
Number | Date | Country | Kind |
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93136119 | Nov 2004 | TW | national |