Centrifugal Fan

Abstract

An arrangement of a low air inlet and a circuit for driving a torque generator in an ultra-compact centrifugal fan is disclosed. In the ultra-compact centrifugal fan, a region occupied by the circuit is not completely arranged radially inside a cup-shaped portion to which an impeller is attached. At least a part of the low air inlet provided on a bottom of a housing of the centrifugal fan is arranged in a range of predetermined angle in an imaginary ring-shaped portion surrounding a base portion covered by the cup-shaped portion. A part of the circuit, that is not covered by the cup-shaped portion, is arranged upstream of the range of the predetermined angle in a flowing direction of airflow.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The above and further features will be more clearly appreciated from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like reference numerals indicate like structures. All of these conventions, however, are intended to be typical or illustrative, rather than limiting.

FIG. 1 is a vertical cross-sectional view of a centrifugal fan according to a preferred embodiment of the present invention.

FIG. 2 is a perspective view showing an appearance of the centrifugal fan of FIG. 1.

FIG. 3 is a perspective view showing inside of the centrifugal fan of FIG. 1.

FIG. 4 is an exploded perspective view of a main structure of the centrifugal fan of FIG. 1.

FIG. 5 is a plan view showing the inside of the centrifugal fan of FIG. 1.

FIG. 6 is a plan view of a circuit board and a housing body of FIG. 1.

FIG. 7 illustrates a bottom of a housing in a simplified manner.

FIGS. 8A to 8D illustrate housings each having a lower air inlet that is open in a range of 270° in a simplified manner.

FIGS. 9A to 9D illustrate housings each having a lower air inlet that is open in a range of 180° in a simplified manner.

FIG. 10 shows PQ curves of centrifugal fans each having the 270° lower air inlet.

FIG. 11 shows PQ curves of centrifugal fans each having the 180° degree lower air inlet.

FIGS. 12A to 12L illustrate housings each having a lower air inlet that is open in a range of 90° in a simplified manner.

FIGS. 13A to 13L illustrate housings each having a lower air inlet that is open in a range of 45° in a simplified manner.

FIG. 14 shows PQ curves of centrifugal fans each having the 90° lower air inlet.

FIG. 15 shows PQ curves of centrifugal fans each having the 45° lower air inlet.

FIG. 16 illustrates an impeller according to another preferred embodiment of the present invention.

FIG. 17 illustrates a housing according to another preferred embodiment of the present invention.

Claims

1. A centrifugal fan comprising: a shaft rotating around a rotation axis;a cup-shaped portion opening downward and attached to the shaft;a plurality of blades arranged outside the cup-shaped portion in a radial direction perpendicular to the rotation axis, the blades rotating together with the shaft and generating an airflow;a magnet and an armature both arranged within an opening of the cup-shaped portion and generating a torque for rotating the shaft, the cup-shaped portion, and the blades;a housing having top and bottom faces axially opposed to each other and a side face, and accommodating the shaft, the cut-shaped portion, the blades, and the magnet and armature, wherein the bottom face has an air inlet for taking an air into the housing, the side face has an air outlet for discharging the air, the bottom face includes a base portion opposed to the cup-shaped portion and a ring-shaped region surrounding the base portion and opposed to the blades, the housing defining a path of the airflow with the air outlet arranged at a downstream end; anda circuit supplying an electrical power to the armature and located on the bottom face of the housing, wherein: a portion of the bottom face with the circuit located thereon includes a first part located in the base portion of the bottom face and a second part located in the ring-shaped region;at least a part of the air inlet is located in a range of a predetermined angle in the ring-shaped region; andthe second part of the portion with the electric circuit formed thereon is located upstream of the range of the predetermined angle in a flowing direction of the airflow.

2. The centrifugal fan according to claim 1, wherein the range of the predetermined angle is ±45° around the rotation axis from an edge of the air outlet farthest from an upstream end of a path of the airflow.

3. The centrifugal fan according to claim 1, wherein the range of the predetermined angle is outside of a range of 255° to 330° from an imaginary reference line with respect to the rotation axis in a direction opposite to the flowing direction, the imaginary reference line being shortest one of lines connecting the rotation axis to the air outlet.

4. The centrifugal fan according to claim 1, wherein the range of the predetermined angle is ±45° around the rotation axis from a position in the air outlet that provides a largest flow rate.

5. The centrifugal fan according to claim 1, wherein the circuit is formed by a circuit board on which an electronic part is mounted, the circuit board is formed on the portion of the bottom face with the circuit located thereon in such a manner that a part of the circuit board is located on the base portion and a remaining part is located in the imaginary ring-shaped region.

6. The centrifugal fan according to claim 1, wherein: a diameter of the cup-shaped portion is 10 mm or less; andthe portion of the bottom face with the electric circuit formed thereon has an outer shape which includes a part uncovered with the cup-shaped portion, when seen in an axial direction along the rotation axis.

7. The centrifugal fan according to claim 1, further comprising another air inlet formed in the top face.