Working principle of piston air compressor

Working principle of piston air compressor
The working principle of a piston air compressor is to convert the rotational motion of the motor into the reciprocating linear motion of the piston through a crank connecting rod mechanism, periodically changing the volume of the enclosed space in the cylinder, and cooperating with a valve system to achieve gas suction, compression, and discharge. Its working process is divided into four stages

1. Inhalation process
When the piston moves downwards, the cylinder volume increases, and the internal air pressure is less than atmospheric pressure. The intake valve opens under the pressure difference, and external air is sucked into the cylinder. When the piston reaches its lowest point, the cylinder is filled with low-pressure gas and the suction valve closes.

2. Compression process
When the piston moves upward, the cylinder volume decreases, the intake/exhaust valves are closed, the gas is compressed in a closed manner, and the pressure and temperature continue to increase. When the pressure inside the cylinder rises slightly above the pressure in the exhaust pipe, the exhaust valve is pushed open.

3. Exhaust process
The piston continues to move to the left, and the compressed gas is output to the compressed air pipeline through the exhaust valve at a stable pressure. When the piston reaches its highest point, the exhaust ends and the exhaust valve closes.

4. Expansion process
When the exhaust is completed, there is residual volume between the piston and cylinder head, with a small amount of high-pressure gas remaining. When the piston moves to the right again, the high-pressure gas in the clearance expands first until the pressure drops below the suction pressure, and then the intake valve reopens. It will reduce the actual inhalation volume and decrease efficiency.


Advantages of piston air compressor
1. Pressure range
0.5~350MPA， Can meet the requirements of high-pressure painting and storage.

2. Simple structure
The main components are made of ordinary steel, which has relatively low maintenance costs.

3. Good thermal efficiency performance
The heavy-duty thermal efficiency group can reach 0.7 with low energy consumption.

4. Wide range of displacement
Adapt to different loads through multi cylinder parallel connection or stroke adjustment

Disadvantages of piston air compressor
1. High noise level
The reciprocating motion leads to high inertia force and high noise in the working environment.

2. There are fluctuations in the exhaust
Unstable airflow, gas storage tank is required to relieve pressure

Industrial application of piston air compressor
1. Forging workshop
Provide air source for equipment such as molding machines.

2. Automobile production
Provide compressed air for the tire assembly line.

3. Ship maintenance
Ship repair yard, piston type air compressor supplies air to the pneumatic polishing tool group, ensuring that the air pressure fluctuation does not exceed ± 0.02Mpa during continuous 8-hour operation.

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