Cylinder is the main component of compression volume. Requirements for cylinder: sufficient strength, stiffness and wear resistance; Good cooling conditions; Small flow resistance (large enough air flow channel area and air valve installation area); Minimize the clearance volume; Reasonably increase the volume of the valve chamber and reduce the air flow pressure pulse. General material: cast iron.    

The cylinder is composed of air valve chamber, water channel, cylinder block, cylinder head, etc. there is usually no cylinder liner. According to the action mode, there are three structural forms: single action type, double action type and differential type; According to the cooling mode, there are air cooling and water cooling.  

Layout principle of air valve on cylinder: the installation area of air valve is large, that is, the air flow channel area is large, the resistance loss is small, the installation and maintenance are convenient, and the clearance volume is small.  

(the stage of the compressor is mainly determined according to the compression ratio, that is, the ratio of exhaust pressure to suction pressure of the compressor. The purpose of multi-stage compression is to reduce the exhaust temperature, save power, reduce the gas force acting on the piston and improve the volumetric efficiency of the cylinder. The economy of large and medium-sized compressors operating continuously for a long time is very important, so the stages are selected according to the highest efficiency point, and the corresponding compression ratio at all levels is between 2-4. The cylinder and piston assembly corresponding to each connecting rod is called a column. The use of multi column compression can balance the reciprocating inertia force of the compressor completely or mostly, simplify the structure of each column and reduce the maximum gas force of the column. However, the increase in the number of columns will complicate the overall structure of the compressor and increase the number of parts and components.