Patent ID: 8403651

Claim:
An airflow guiding structure, applied to a fan, the fan comprising an impeller, a circuit board, a motor and a guiding ring, the impeller having a hub and a plurality of axial-flow blades disposed around the hub, the guiding ring is connected with the axial-flow blades, wherein: an outer radius of the airflow guiding structure increases gradually from a top of the airflow guiding structure to a bottom of the airflow guiding structure, an inlet is formed on a top of the guiding ring, and an outlet is formed between a bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure, wherein a first predetermined distance is defined between the top of the guiding ring and the top of a conjunction of the guiding ring and the axial-flow blades, and a ratio of the first predetermined distance to the length of a conjunction of the axial-flow blades and the hub ranges from 0.3 to 1; when the impeller rotates, an airflow enters the fan from the inlet and flows along the outer surface of the sidewall of the airflow guiding structure, then the airflow exits the fan through the outlet, and the direction of the airflow passing through the outlet is different from the direction of the airflow passing through the inlet; wherein an inner surface of the guiding ring is connected with outer edges of the axial-flow blades, and the circuit board and at least a portion of the motor are disposed in an accommodating space formed inside the airflow guiding structure.