Patent ID: 7976293
Filing Date: 2011-07-12
Classification: F01D,F04D

Abstract:
1. A centrifugal fan comprising: an impeller including a plurality of blades arranged about a center axis; a motor arranged to rotate the impeller about the center axis; a control circuit arranged to control the motor and including a circuit board, a plurality of electronic components mounted on the circuit board, and a component mounting portion on which at least one of the electronic components is mounted; and a casing arranged to house the impeller, the motor, and a portion of the control circuit; wherein the casing includes an axially arranged intake port, an exhaust port arranged to extend away from the center axis and having an opening end surface parallel or approximately parallel to the center axis, and a circumferential wall surrounding the impeller; the circumferential wall is arranged such that a radial distance of the circumferential wall from an outer periphery of the impeller gradually increases in a circumferential direction; the circuit board is arranged on an axial lower side of the impeller opposite to the intake port and the circuit board is also arranged entirely on an exhaust port side of the centrifugal fan with respect to the center axis such that an imaginary straight line may extend radially through the center axis and will not pass through any portion of the circuit board; and at least a portion of the circuit board is disposed in a space between a virtual plane extending from the opening end surface and the circumferential wall, and the component mounting portion is disposed in the space; wherein all of said electronic components mounted on the circuit board are disposed within said space; and wherein the component mounting portion is enclosed by sidewalls and a top plate, the sidewalls are parallel or substantially parallel to the center axis, the to plate is continuous with an upper wall of the casing, and the sidewalls and the to plate are integral with the casing.