Fan structure having a first impeller and a second impeller

摘要

A fan structure comprises a first impeller and a second impeller, wherein the first impeller is composed of a first annular substrate, a plurality of first ribs and a plurality of first blades. The first ribs and the first blades are formed on the first annular substrate, each of the first ribs comprises an engaging hole, and a first accommodating space is formed between each of the adjacent first blades. The second impeller is composed of a hub, a second annular substrate, a plurality of second ribs, a plurality of second blades and at least one engaging member formed on the second ribs. The second ribs and the second blades are formed on the second annular substrate, and a second accommodating space is formed between each of the adjacent second blades. The first blades and the second blades are arranged in a staggered relationship.