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.

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.