Air blower and combustion device including the same

An air blower, comprising:

• a casing, having an air intake port and an air blowing port;
• and
• an impeller, housed in the casing and rotating,
• wherein the impeller comprises a plurality of blades arranged at intervals in a circumferential direction so as to form a plurality of inter-blade passages, and a region closer to a center than the plurality of blades serves as a central space portion communicating with the plurality of inter-blade passages,
• when the impeller rotates, air flowing into the central space portion through the air intake port passes through the plurality of inter-blade passages at a radially outward side of the impeller, and
• wherein to reduce noise generated when the air passes through the plurality of inter-blade passages, each of the blades comprises:
• a plurality of first concavo-convex portions, with a first surface side being concave and a second surface side on the other side being convex, from among a first surface and a second surface corresponding to a front surface and a rear surface of each of the blades;
• and a plurality of second concavo-convex portions, with the second surface side being concave and the first surface side being convex, contrary to the first concavo-convex portions,
• wherein the plurality of first concavo-convex portions and the plurality of second concavo-convex portions are arranged in a plurality of rows in a radial direction and a width direction of the impeller intersecting each other, and the rows of the first concavo-convex portions and the rows of the second concavo-convex portions are staggered and alternately arranged in the radial direction and the width direction.

An air blower, comprising:

• a casing, having an air intake port and an air blowing port;
• and
• an impeller, housed in the casing and rotating,
• wherein the impeller comprises a plurality of blades arranged at intervals in a circumferential direction so as to form a plurality of inter-blade passages, and a region closer to a center than the plurality of blades serves as a central space portion communicating with the plurality of inter-blade passages,
• when the impeller rotates, air flowing into the central space portion through the air intake port passes through the plurality of inter-blade passages at a radially outward side of the impeller, and
• wherein to reduce noise generated when the air passes through the plurality of inter-blade passages, each of the blades comprises:
• a plurality of first concavo-convex portions, with a first surface side being concave and a second surface side on the other side being convex, from among a first surface and a second surface corresponding to a front surface and a rear surface of each of the blades;
• and a plurality of second concavo-convex portions, with the second surface side being concave and the first surface side being convex, contrary to the first concavo-convex portions,
• wherein a total frontal view projection area of the plurality of first concavo-convex portions and the plurality of second concavo-convex portions in each of the blades is larger than a total area of non-concavo-convex portions interposed between the plurality of first concavo-convex portions and the plurality of second concavo-convex portions, or
• wherein a total frontal view projection area of the plurality of first concavo-convex portions and the plurality of second concavo-convex portions in each of the blades plus the non-concavo-convex portions interposed therebetween exceeds half of an area of each of the first and second surfaces of each of the blades.