Patent ID: 7909572

Claim:
A shroud of a propeller fan including a rotary vane wheel driven by a rotary vane wheel driving unit, the shroud comprising: a mount configured to attach and support the rotary vane wheel driving unit; and a support beam that radially extends from the mount, joins the mount to a body portion of the shroud, has a thickness that increases from an upstream end to a downstream end of a flow direction of air discharged by the rotary vane wheel, includes a downstream edge portion at the downstream end of the flow direction, the downstream edge portion being oriented in a direction parallel to a rotation axis of the rotary vane wheel and an upstream edge portion at the upstream end of the flow direction, the upstream edge portion being inclined to be oriented in a direction opposite to a rotation direction of the rotary vane wheel, and has a cross sectional form formed of: two envelopes of circles arranged on an arc about a virtual center point, the circles having different radii decreasing from a downstream end to an upstream end of the arc, the arc being a center line of a cross section of the support beam, the cross section being orthogonal to a longitudinal direction of the support beam; an arc of a most downstream one of the circles; and an arc of a most upstream one of the circles.