Cross-section "Micro Cooling Fan" axial fan is usually a wing section. Blade position can be fixed, to be rotated about its longitudinal axis. Blade pitch angle or blade and the air flow can not be adjusted or adjustable. Change the blade angle or pitch is one of the main advantages of axial fans. Small blade pitch angles produce lower flows while increasing the pitch may result in higher traffic. Advanced "Micro Cooling Fan" axial fan blade pitch can be changed (which is quite similar to a helicopter rotor) during fan operation, thus changing the flow accordingly. This is called variable pitch (VP) axial fans. When the impeller rotates, the gas from the inlet axially into the impeller by the "Micro Cooling Fan" on impeller blades push the gas by the energy increases, and then flows into the vanes. Vanes will deflect airflow into axial flow, while gas is introduced into the diffuser tube, and further the gas kinetic energy is converted to pressure energy, and finally to introduce the work of the pipeline.