1) cylinder:
Cylinder is one of the main components of compressor, which should have good surface for lubrication and wear resistance, and good thermal conductivity, so that the heat energy generated by friction can be radiated at the fastest speed; There should also be a large enough air flow passage area and air valve installation area, so that the volume of the valve cavity can just reduce the pressure pulsation amplitude of the air flow, thus ensuring the normal operation of the air valve and reducing power consumption. The clearance volume should be smaller to improve the efficiency of the compressor.
2) Crank connecting rod mechanism:
The mechanism includes crosshead, connecting rod, crankshaft and sliding guide rail. -It is the main operation and transmission component, which converts the circular motion of the motor into the reciprocating motion of the piston through the connecting rod, and it is also the main stress component.
3) Piston assembly:
There are mainly piston heads, piston rings, support shoes and piston rods. The shape and size of piston are closely related to cylinder, which can be divided into double-acting piston and single-acting piston. The piston ring is used to seal the high-pressure gas in the cylinder and prevent the gas from leaking from the gap between the piston and the cylinder. As the name implies, the bearing bush is used to support the piston, so the bearing bush is also a vulnerable part, and the quality of the bearing bush material also directly affects the service life of the compressor.
4) filler:
Piston rod seal is mainly used to seal the gap between the inner seat of the cylinder and the piston rod to prevent gas from leaking along the radial direction of the piston rod. The manufacture and installation of packing ring involves "three shortages". They are axial clearance (to ensure that the packing ring can float freely in the ring groove), radial clearance (to prevent the packing ring from being deformed or damaged due to the sinking of the piston rod) and tangential clearance (to compensate for the wear of the packing ring).
5) Air valve:
It is the most important part of the compressor, and it is also the most easily damaged part. The quality of its design will directly affect the displacement, power consumption and operation reliability of the compressor. A good air valve should have the following characteristics: high efficiency and energy saving (accounting for 3%~7% of shaft power), perfect combination of air tightness and timely action, long service life (generally, the actual service life is 8000h), small clearance volume, low noise, small temperature rise, and can be refurbished.
Extended data
The working process of reciprocating compressor can be divided into four processes: expansion, suction, compression and exhaust.
Example: Only one section of the cylinder of a single suction compressor has a suction valve and a discharge valve, and the piston only sucks and discharges air once every reciprocating motion.
(1) Expansion: When the piston moves to the left, the volume of the cylinder increases, the pressure drops, and the residual gas in the cylinder expands continuously.
(2) Suction: When the pressure drops to slightly less than the gas pressure in the intake pipe, the gas in the intake pipe pushes open the suction valve and enters the cylinder. As the piston moves to the left, gas continues to enter the cylinder until the piston moves to the left end (also known as the left dead center).
(3) Compression: When the piston moves to the right, the volume of the cylinder gradually shrinks, thus starting the process of compressing gas. Because the suction valve has a check function, the gas in the cylinder cannot flow back into the intake pipe, and the gas pressure in the exhaust pipe is higher than that in the cylinder, so the gas in the cylinder cannot run out of the cylinder from the exhaust valve.
Due to the check function of the exhaust valve, the gas in the exhaust pipe cannot flow into the cylinder. Therefore, the amount of gas in the cylinder remains unchanged, because the piston continues to move to the right, reducing the gas-containing space (volume) in the cylinder and increasing the pressure of gas.
(4) Exhaust: As the piston moves to the right, when the pressure of compressed gas rises to slightly higher than the pressure in the air outlet pipe, the gas in the cylinder pushes the spring of the exhaust valve into the air outlet pipe and is continuously exhausted until the piston moves to the right end (also called right dead center). Then, the piston starts to move to the left again and repeats the above actions.
The piston keeps moving back and forth in the cylinder, which makes the cylinder suck and discharge gas back and forth. Every reciprocating motion of the piston becomes a working cycle, and the distance traveled by the piston every time it comes or goes back is called stroke.