Fan and airflow guiding structure thereof

An airflow guiding structure applied to an axial-flow fan, the axial-flow fan comprising an impeller, a circuit board, a motor and a guiding ring, the impeller comprising a hub and a plurality of blades disposed around the hub, wherein:

• the airflow guiding structure is disposed underneath the impeller, 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, the guiding ring is connected to a module housing or connected to the airflow guiding structure via at least one connecting element, a predetermined distance is arranged between an inner surface of the guiding ring and outer edges of the blades, an inlet is formed at a top of the guiding ring, an outlet is formed between a bottom of the guiding ring and an outer surface of a sidewall of the airflow guiding structure, and a first predetermined distance is defined between the top of the guiding ring and a top of the blades, and a ratio of the first predetermined distance to the length of a conjunction of the blades and the hub ranges from 0.3 to 1;
• when the impeller rotates, the 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 a direction of the airflow passing through the outlet is different from a direction of the airflow passing through the inlet;
• wherein the circuit board and at least a portion of the motor are disposed in an accommodating space formed inside the airflow guiding structure.

A fan, comprising:

• an airflow guiding structure whose outer radius increases from a top of the airflow guiding structure to a bottom of the airflow guiding structure;
• an impeller disposed on the airflow guiding structure and comprising a hub and a plurality of blades disposed around the hub;
• a motor disposed in the hub;
• a covering plate connected with the airflow guiding structure;
• a circuit board for driving the motor, wherein the circuit board is disposed in an accommodating space formed inside the airflow guiding structure and closed via the covering plate;
• and
• a guiding ring connected to a module housing or connected to the airflow guiding structure via at least one connecting element, wherein an inlet is formed at 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 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 a direction of the airflow passing through the outlet is different from a direction of the airflow passing through the inlet.