Patent ID: 8007240

Claim:
An impeller of a centrifugal fan comprising: a main plate configured to rotate around a rotating shaft, the main plate being constructed of resin material; a plurality of hollow blades annularly disposed around the rotating shaft, each of the hollow blades including a first surface portion integrally molded with or fixed to the main plate, the first surface portion being constructed of resin material, and a second surface portion attached to the first surface portion to form a hollow space therebetween, the second surface portion being constructed of resin material; and a side plate fixed to the first surface portions by laser welding, the side plate being constructed of resin material and being molded separately from the first surface portions, the hollow blades being disposed between the main plate and the side plate, the main plate, the hollow blades and the side plate being configured to take in a gas from a rotating shaft direction and blow out the gas in a direction intersecting the rotating shaft, each of the second surface portions forming at least part of a negative-pressure surface, and each of the first surface portions forming at least part of a positive pressure surface, the hollow blades including a blade shape retaining mechanism to prevent the second surface portions from being deformed toward outer peripheral sides of the second surface portions by a centrifugal force, each of the first surface portions having an edge portion extending from a side plate end thereof toward a respective one of the second surface portions, with each edge portion being laser welded to the side plate, each edge portion having an end surface that abuts a lateral surface of the respective one of the second surface portions at a side plate end thereof to form part of the blade shape retaining mechanism and to define a side plate end of the hollow space, and the lateral surfaces of the second surface portions facing the first surface portions with the hollow spaces therebetween, the side plate ends of the hollow spaces, the first surface portions and the second surface portions being disposed at ends of the blades closer to the side plate than the main plate, and each blade having a leading rotational edge and a trailing rotational edge with the edge portion of the first side portion extending between the leading and trailing rotational edges of the blade such that an interior surface of the edge portion faces the main plate with the hollow space of the blade disposed between the interior surface of the edge portion and the main plate, the hollow space having a length measured between the leading and trailing rotational edges of the blade, and the edge portion extending along the entire length of the hollow space between the leading and trailing rotational edges of the blade.