Fan impeller and fan motor

Abstract

Small, high-performance centrifugal fan for cooling portable electronic devices. The centrifugal fan motor employs a cantilever-type impeller constituted by an impeller blade unit that includes a lower endwall portion at axial one end, having a wall surface for breaking the flow of air along the rotational axis, and an opening at the other axial end. The impeller is configured so that the radius r to the outer circumference of the impeller blade unit is smaller than the axial height h of the impeller. When an airflow that enters through the impeller opening is forced out towards outer periphery of the impeller blade unit, windage loss at the wall surface of the lower endwall portion of the impeller is reduced, which realizes high-efficiency cooling performance that complements motor performance.

Description

BACKGROUND OF INVENTION [0001] 1. Technical Field [0002] The present invention relates to cooling-fan motors and impellers that are used in electronic devices and the like. More specifically, the present invention relates to fan motors that must generate high static pressure and ample airflow volume, and to cantilever-type impellers that are used in such fan motors. [0003] 2. Description of the Related Art [0004]FIG. 8 is a plan view of a conventional centrifugal fan motor. FIG. 9 is a vertical cross section along the line X1-O1-Y1-Z1 in FIG. 8. This centrifugal fan motor includes a motor component 104 for generating rotational driving force, an impeller component 101 for generating airflow, and a housing 106. This centrifugal fan motor has a rotational axis 01 shown in FIG. 8. [0005] The impeller component 101 is located around the outer periphery of the motor component 104 and includes a lower end wall 102 and blades 103. The lower end wall 102 is an annular plate member located s...

AI Technical Summary

Benefits of technology

[0009] An object of the present invention is to realize a fan motor that can be used for ultra-compact devices such as cellular phones, and that is ultrasmall in size and has high cooling efficiency, as well as to realize an impeller that is used for a fan motor of this sort. Another object of the present invention is to make available a fan motor capable of realizing maximum cooling efficiency with minimum air-inlet area, as well as to make available an impeller that is used for such a fan motor.

[0010] According to the present invention, a cantilever-type fan impeller comprises: a rotational force transmission portion for receiving driving force from a fan motor component; a lower endwall portion fixed in association with the rotational force transmission portion, for structuring a wall surface that is perpendicular to the impeller rotational axis; and an impeller blade unit having plural blades, disposed outer-marginally on the wall surface of the lower endwall portion and extending along rotational axis. When the fan impeller rotates, an airflow along the rotational axis, from the opening in the upper end of the impeller blade unit towards the wall surface, is generated. The relationships 2r≦h and r≦12.5 mm are satisfied wherein 2r represents the diameter to outer circumference of the impeller blade unit and h represents the axial height of the impeller blade unit. In this fan impeller, when driving force is applied from the motor component to the rotational force transmission portion, the lower endwall portion and the impeller blade unit rotate along with the rotation force transmission portion. Then, an airflow along the rotational axis, from the opening in the upper end of the impeller blade unit towards the wall surface that is perpendicular to the axis, is generated. Next, the airflow hits the wall surface and changes direction. Since 2r≦h, windage loss at the wall surface of the lower endwall portion is reduced compared with conventional centrifugal fans, so that cooling efficiency is improved.

Problems solved by technology

The windage loss on the wall surface can decrease airflow volume from the fan and lower the cooling efficiency below the inherent performance of the fan motor.

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