The working principle of a screw piston compressor can be divided into two main stages: the screw compression stage and the piston compression stage.

1. Screw Compression Stage:
   
   • Low-pressure gas enters the screw compressor section first.
   • The screw rotors rotate, and the gas is pre-compressed by the reduction of the volume between the rotor lobes.
   • This stage is primarily responsible for increasing the initial gas pressure.
2. Piston Compression Stage:
   
   • The pre-compressed gas then enters the piston compressor section.
   • The piston reciprocates within the cylinder, further compressing the gas to the desired high pressure.
   • This stage is responsible for achieving the final high-pressure output.

Components:

Screw piston compressors mainly consist of the following parts:

1. Screw Compressor Section:
   
   • Screw Rotors: Responsible for the initial compression of the gas.
   • Casing: Houses the screw rotors, forming the compression chamber.
   • Inlet and Outlet Ports: Control the gas flow in and out.
2. Piston Compressor Section:
   
   • Cylinder: Where the piston reciprocates.
   • Piston: Responsible for further compressing the gas.
   • Connecting Rod: Connects the piston to the crankshaft, transmitting power.
   • Crankshaft: Converts rotary motion into the piston’s reciprocating motion.
   • Valves: Control the gas flow in and out, including intake and discharge valves.
3. Drive System:
   
   • Motor: Provides power.
   • Transmission System: Transmits the motor’s rotary motion to the screw rotors and crankshaft.
4. Cooling System:
   
   • Because the compression process generates heat, the cooling system is used to maintain the compressor’s normal operating temperature.
   • Cooling methods can be air-cooled or water-cooled.
5. Lubrication System:
   
   • The lubrication system reduces friction between moving parts and extends the compressor’s service life.
6. Control System:
   
   • The control system monitors and controls the compressor’s operating parameters, such as pressure and temperature.

Working Characteristics:

• Combines the high efficiency of screw compressors with the high-pressure capability of piston compressors.
• Suitable for applications requiring relatively high pressure and a certain flow rate.
• Relatively complex structure with higher maintenance requirements