Axial-flow fan

Abstract

An axial-flow fan according to the present disclosure can increase the amount of the airflow and simultaneously reduce the noise level. A plurality of stationary blades 11A to 11D are curved, in a convex manner, toward a rotating direction of an impeller. The plurality of stationary blades 11A to 11D are generally inclined so that discharge-side edge portions 11d thereof are located more forward than suction-side edge portions 11c thereof in the rotating direction. An inclination angle θ4 of each of the plurality of stationary blades 11A to 11D in the vicinity of the external end portion 11a is larger than the inclination angle θ3 in the vicinity of the internal end portion 11b. The inclination angle is gradually changed from the vicinity of the external end portion 11a toward the vicinity of the internal end portion 11b.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an axial-flow fan used for cooling an electric component or the like. BACKGROUND OF THE INVENTION [0002]FIG. 16 is a perspective view of an axial-flow fan equipped with stationary blades shown in FIG. 1 of US Design Patent No. D506540 (Official Gazette) FIG. 17 is a rear view of a conventional axial-flow fan shown in FIG. 5 of the same Official Gazette. As shown in these figures, in conventional axial-flow fans equipped with stationary blades, each of a plurality of stationary blades 101 is curved, in a convex manner, toward one side in a circumferential direction of a shaft. The plurality of stationary blades 101 are generally inclined so that the suction-side edge portions 101 are located at an opposite side to the suction-side edge portions in the circumferential direction of the shaft. The plurality of stationary blades are inclined at a substantially constant angle. [0003] However, it is impossible for the conventio...

AI Technical Summary

Benefits of technology

[0004] An object of the present invention is to provide an axial-flow fan capable of increasing the amount of airflow and simultaneously reducing the noise level.

[0005] Another object of the present invention is to provide an axial-flow fan capable of entirely cooling an object to be cooled even when the distance between an object to be cooled and an air discharge opening of the axial-flow fan is short.

[0008] The flow rate of air discharged from the air discharge opening of the axial-flow fan tends to become faster in an area closer to the fan housing (in an outer side) while the flow rate tends to become slower in an area closer to the motor case (in an inner side). This tendency is the same when stationary blades of a simple shape are used. According to the present invention, by arranging all or most of the plurality of stationary blades as described above, the flow rate of the airflow flowing in the vicinity of the internal end portions of the stationary blades is increased with respect to the flow rate of the airflow flowing in the vicinity of the external end portions of the stationary blades. The flow rate of the airflow is gradually increased from the external end portion toward the internal end portion of the stationary blades. As a result, the flow rate of the air discharged from the air discharge opening is generally uniformized as much as possible, thereby increasing an amount of the airflow and simultaneously reducing the noise level.

[0012] The outer surface of the bottom wall portion of the motor case is composed of a flat bottom surface and an outer peripheral surface portion continuous with the flat bottom surface. It should be noted that the flat bottom surface includes not only an entirely flat surface but also a surface of which the major part is flat. For example, a bearing for supporting the shaft may be disposed in the central area of the bottom surface. In this case, the outer peripheral surface portion is preferably shaped to be gradually curved from the bottom surface toward the outer peripheral surface of the peripheral wall portion. With this arrangement, the air flowing along the stationary blades toward the motor case can smoothly run onto the bottom surface of the motor case. As a result, the amount of the air, which flows from the bottom surface of the motor case toward the air discharge opening, can be increased.

[0014] Further, the extended portion preferably includes an extended guide surface, which is formed continuously with the guide surface and is extending toward the rotating direction. The extended guide surface helps the airflow, which has run onto the bottom wall portion of the motor case, get spirally out of the air discharge opening smoothly.

[0015] According to the present invention, the amount of airflow produced by the axial-flow fan can be increased more and simultaneously the noise level can be reduced more than ever.

Problems solved by technology

However, it is impossible for the conventional axial-flow fan to increase an amount of airflow and to simultaneously reduce the noise level without modifying the structure thereof.

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