Patent ID: 8181479

Claim:
An inlet guide vane configured for a suction port into which a fluid is sucked by rotation of an impeller, the inlet guide vane positioned so as to be rotatable about an axis, and configured to adjust a suction volume and flow direction of the fluid to the suction port, the inlet guide vane comprising: a rod-like shaft positioned and configured to be supported by an inner peripheral surface of the suction port so as to be rotatable about the axis, and a plate-like vane body that is connected to the shaft and positioned so as to protrude from the inner peripheral surface of the suction port toward a central portion thereof, wherein the vane body has a first side surface on a side which becomes positive pressure and a second side surface on the side which becomes negative pressure, at the time of adjustment of the suction volume and flow direction of the fluid, the vane body includes: a tapered portion formed such that the first and second side surfaces approach each other toward an outer edge of the vane body in its width direction and an outer edge thereof at a tip in the direction of the axis, and a parallel portion arranged on the axis and formed such that the first side surface on the side which becomes positive pressure and the side surface on the side which becomes negative pressure is parallel to the second side surface along the direction of the axis, and a length of the parallel portion in the direction of the axis is ¼ to ½ of the length of the vane body in the direction of the axis.