The main engine of silent oilless air compressor generally adopts miniature reciprocating piston compressor. The working principle of the main engine is as follows:

When the crankshaft of the compressor is driven by the single shaft of the motor to rotate, the piston with self-lubrication and without any lubricant will do reciprocating movement through the transmission of the connecting rod, and the working volume formed by the inner wall of the cylinder, the cylinder head and the top surface of the piston will change periodically. When the piston of the piston compressor starts to move from the cylinder head, the working volume in the cylinder increases gradually. At this time, the gas enters the cylinder along the air inlet pipe and pushes the air inlet valve.

When the piston of the piston compressor moves in the opposite direction, the working volume in the cylinder shrinks and the gas pressure increases. When the pressure in the cylinder reaches and is slightly higher than the exhaust pressure, the exhaust valve opens and the gas is discharged into the cylinder until the piston moves to the limit and the exhaust valve closes.

This process is repeated when the piston of the piston compressor moves in the opposite direction again. Namely: the crankshaft of the piston compressor rotates once, the piston reciprocates once, and the process of air intake, compression and exhaust is realized successively in the cylinder, which completes a working cycle. The structure design of uniaxial double cylinder makes the gas flow rate of the compressor double that of the single cylinder when the rated speed is fixed, and the vibration and noise control is well controlled.

However, there are a few pseudo-silent type oilless air compressor in the market, which is not a miniature reciprocating piston compressor. It can be definitely judged that this type of air compressor is not a silent oilless air compressor, and the air quality cannot meet the requirements of the silent oilless air compressor.