The fan is mainly composed of six parts: motor, air filter, fan body, air chamber, base and oil drop nozzle. The blower operates eccentrically through the eccentric rotor in the cylinder, changing the volume between blades in the rotor slot to suck, compress and spit out air. During operation, the lubricating oil is automatically sent to the drip nozzle by using the pressure difference of the blower and dripped into the cylinder to reduce friction and noise, and at the same time, the gas in the cylinder can be prevented from flowing back.