CENTRIFUGAL FAN

Abstract

In a centrifugal fan including a casing, a rotatable impeller disposed in the casing, a motor for driving the impeller, a control board for controlling the motor, and an ejection port for cooling air, a dust proof projection is formed to the casing to prevent invasion of dusts from the ejection port to the motor and the control board. With this simple arrangement, invasion of dusts to a coil portion and a control board of the motor can be reduced while suppressing a manufacturing cost. In this case, when the dust proof projection is disposed to a gap between the inner peripheral surface of a side wall of the casing and the outer peripheral surface of the impeller along the outer peripheral surface of the impeller in an arc-shape, a dust proof effect can be more improved.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view showing a basic arrangement of a centrifugal fan of an embodiment of the present invention;

FIG. 2 is a longitudinal side elevational view showing the basic arrangement of the centrifugal fan of the embodiment of the invention;

FIG. 3 is a longitudinal side elevational view showing an arrangement of a conventional centrifugal fan; and

FIG. 4 is a front elevational view of the conventional centrifugal fan showing a result of analysis of wind directions and velocity of wind when suction flows are caused from an ejection port.

Claims

1. A centrifugal fan comprising a casing, a rotatable impeller disposed in the casing, a motor for driving the impeller, a control board for controlling the motor, and an ejection port for cooling air, wherein a dust proof projection is formed to the casing to prevent invasion of dusts from the ejection port to the motor and the control board.

2. A centrifugal fan comprising a casing, a rotatable impeller disposed in the casing, a motor for driving the impeller, a control board for controlling the motor, and an ejection port for cooling air, wherein a dust proof projection is attached to the casing to prevent invasion of dusts from the ejection port to the motor and the control board.

3. A centrifugal fan according to claim 1 or 2, wherein the dust proof projection is disposed to a gap between the inner peripheral surface of a side wall of the casing and the outer peripheral surface of the impeller along the outer peripheral surface of the impeller in an arc-shape.

4. A centrifugal fan according to claim 3, wherein the dust proof projection is disposed in the vicinity of the ejection port of the centrifugal fan as well as a center angle of the arc-shape thereof is 20° to 90° and preferably about 45°.

5. A centrifugal fan according to claims 1 to 4, wherein an extreme end portion of the dust proof projection is formed in a substantially wedge shape.