Abstract: An axial fan includes a fan frame, an impeller and a motor. The fan frame has a frame body, a base and plural connecting members. The base is disposed at the center of a side of the frame body. The connecting members connect the frame body to the base. The impeller is accommodated in the frame body and disposed on the base. The impeller has a rotating shaft, a hub and plural blades disposed around the hub. The motor is disposed on the base and connects with the rotating shaft to drive the impeller to rotate. When the impeller rotates forwardly, the airflow is induced to flow through the connecting members, blades, and one side of the frame body away from the base. When the impeller rotates reversely, the airflow is induced to flow through the side of the frame body, blades and connecting members.

Abstract: An axial fan includes a fan frame, an impeller and a motor. The fan frame has a frame body, a base and plural connecting members. The base is disposed at the center of a side of the frame body. The connecting members connect the frame body to the base. The impeller is accommodated in the frame body and disposed on the base. The impeller has a rotating shaft, a hub and plural blades disposed around the hub. The motor is disposed on the base and connects with the rotating shaft to drive the impeller to rotate. When the impeller rotates forwardly, the airflow is induced to flow through the connecting members, blades, and one side of the frame body away from the base. When the impeller rotates reversely, the airflow is induced to flow through the side of the frame body, blades and connecting members.

Abstract: An axial fan includes a fan frame, an impeller and a motor. The fan frame has a frame body, a base and plural connecting members. The base is disposed at the center of a side of the frame body. The connecting members connect the frame body to the base. The impeller is accommodated in the frame body and disposed on the base. The impeller has a rotating shaft, a hub and plural blades disposed around the hub. The motor is disposed on the base and connects with the rotating shaft to drive the impeller to rotate. When the impeller rotates forwardly, the airflow is induced to flow through the connecting members, blades, and one side of the frame body away from the base. When the impeller rotates reversely, the airflow is induced to flow through the side of the frame body, blades and connecting members.

Abstract: An anti-air-return fan system includes a motor, a driving control circuit, and a rotation judgment circuit. The driving control circuit is electrically connected to the motor. The driving control circuit has a driving signal for driving the motor to rotate according to the driving signal. The rotation judgment circuit outputs a judgment signal to the driving control circuit when detecting that the motor reversely rotate. The driving control circuit executes a braking according to the judgment signal. The driving control circuit drives the motor to operate when the rotation judgment circuit detects that the motor doesn't rotate reversely.

Abstract: A control method of a fan rotation speed, which controls the operation of a fan set including fans connected in series, is disclosed. The control method includes the steps of acquiring a control factor; judging whether the control factor is less than a first threshold value; executing a first control procedure when the control factor is less than the first threshold value; judging whether the control factor is greater than a second threshold value when the control factor is greater than the first threshold; executing a second control procedure when the control factor is greater than the second threshold value; and executing a third control procedure when the control factor is less than the second threshold value.

Abstract: A fan control method includes the steps of: acquiring a control factor; determining whether the control factor is located in a first range or a second range; executing a first dust removing mode if the control factor is located in the first range; executing a second dust removing mode if the control factor is located in the second range; and executing a normal mode if the control factor is not located in the first range and the second range.

Abstract: An anti-air-return fan system includes a motor, a driving control circuit, and a rotation judgment circuit. The driving control circuit is electrically connected to the motor. The driving control circuit has a driving signal for driving the motor to rotate according to the driving signal. The rotation judgment circuit outputs a judgment signal to the driving control circuit when detecting that the motor reversely rotate. The driving control circuit executes a braking according to the judgment signal. The driving control circuit drives the motor to operate when the rotation judgment circuit detects that the motor doesn't rotate reversely.

Abstract: An axial fan includes a fan frame, an impeller and a motor. The fan frame has a frame body, a base and plural connecting members. The base is disposed at the center of a side of the frame body. The connecting members connect the frame body to the base. The impeller is accommodated in the frame body and disposed on the base. The impeller has a rotating shaft, a hub and plural blades disposed around the hub. The motor is disposed on the base and connects with the rotating shaft to drive the impeller to rotate. When the impeller rotates forwardly, the airflow is induced to flow through the connecting members, blades, and one side of the frame body away from the base. When the impeller rotates reversely, the airflow is induced to flow through the side of the frame body, blades and connecting members.

Abstract: A fan control method includes the steps of: acquiring a control factor; determining whether the control factor is located in a first range or a second range; executing a first dust removing mode if the control factor is located in the first range; executing a second dust removing mode if the control factor is located in the second range; and executing a normal mode if the control factor is not located in the first range and the second range.

Abstract: A control method of a fan rotation speed, which controls the operation of a fan set including fans connected in series, is disclosed. The control method includes the steps of acquiring a control factor; judging whether the control factor is less than a first threshold value; executing a first control procedure when the control factor is less than the first threshold value; judging whether the control factor is greater than a second threshold value when the control factor is greater than the first threshold; executing a second control procedure when the control factor is greater than the second threshold value; and executing a third control procedure when the control factor is less than the second threshold value.