Working principle of screw air compressor and analysis of working principle of each system

1、 motor system:

The single screw air compressor is also called screw air compressor. The meshing pair of the single screw air compressor is composed of a 6-head screw and two 11 tooth star wheels. The worm is engaged with two star gears at the same time, even if the force on the worm is balanced, the displacement is doubled. The screw compressor we usually say generally refers to the twin screw compressor.

Screw type compressor has a pair of rotors with mutually engaged and opposite spiral teeth. The rotor with convex tooth surface is called male rotor, and the rotor with concave tooth surface is called female rotor.

(1) Inspiratory process

When the rotor rotates, a tooth of the male rotor is continuously separated from a tooth slot of the female rotor, and the volume between the teeth is gradually expanded and connected with the suction orifice. The gas enters the volume between the teeth through the suction orifice until the volume between the teeth reaches the maximum value, and is disconnected from the suction orifice.

(2) Compression process

The rotor continues to rotate. Before the volume between the teeth of the male and female rotors is connected, the gas in the volume between the teeth of the male rotor is first compressed by the intrusion of the female rotor teeth; After a certain turning angle, the volume between the male and female rotors is connected to form a "V" shaped volume pair between the teeth (primitive volume). As the two rotor teeth squeeze into each other, the primitive volume is gradually moved and the volume is gradually reduced, realizing the gas compression process. The compression process lasts until the unit volume is connected with the exhaust orifice.

Disadvantages:

1. The machining accuracy of the spatial curved surface of the spiral rotor is required to be high;

2. The meshing line between rotors cannot achieve good interstage sealing and is limited by rotor stiffness. At present, the screw compressor cannot reach a high end pressure;

3. Due to the above characteristics, screw compressors are generally used in the following working conditions:

1. The flow is not very high

2. Long period smooth operation is required

3. Low exhaust pressure

Casing:

It is composed of the body, suction end seat and exhaust end seat, and is the main component of the compressor. The engine block is the central part connecting all parts, which provides correct assembly position for all parts, and ensures that the male and female rotors mesh in the cylinder and work reliably. Its end face shape is ∞ shape, which is suitable for the external cylindrical surfaces of two meshing rotors, so that the rotors can be accurately installed into the machine body.

Rotor:

The main components for variable volume compression are composed of male and female rotors. The tooth profile of rotor is processed by high-precision special machine tools and special cutters, which is one of the key parts of compressor.

1. The male rotor and the motor are connected as the active rotor, which transmits torque, and drives the female rotor (driven rotor) to rotate through the meshing relationship.

2. The male and female rotors mesh with the driving gear driven by the motor through their respective driven gears to transmit torque.

Bearing:

The bearing is a part that supports the male and female rotors and ensures the high-speed rotation of the rotor.

The lubricating oil enters the compressor through the mixing of lubricating oil and cost saving, and the machine is lubricated and sealed with the flow of medium. Its advantages are as follows:

1) Reduce the exhaust temperature.

2) Reduce leakage of working medium and improve sealing effect.

2、 Cooling/separation system:

The cooling system is one of the most important parts of the air compressor, because a lot of heat is released after the air is compressed, and the heat is taken away by the cooling system after heat exchange. The cooling system is divided into air cooling type and water cooling type.

(1) Air cooled cooling system

The air-cooled cooling system consists of two parts: fan and cooler. The cooler adopts aluminum plate fin heat exchanger.

Attention shall be paid to the use of air-cooled units:

1. The temperature of the cold air (basically equivalent to the ambient temperature) is very important and should not be too high. It is recommended not to exceed 40 ℃.

2. When the cooler is exposed to air, the fins will be stained with dust. If too much dust is collected, the heat exchange effect of the cooler will be seriously affected. Therefore, the dust on the surface of the fin shall be blown off frequently with compressed air. If the situation is serious and cannot be blown clean, the cleaning agent must be used. When cleaning the unit parts, it is strictly prohibited to use flammable, explosive and volatile cleaning agents.

When cleaning, remove the cover plate on the side of the cooler bracket and use a hand-held air gun to blow upward.

(2) Water cooled cooling system

Shell and tube cooler is adopted. One is the rear cooler used to cool the compressed air, and the other is the oil cooler used to cool the lubricating oil sprayed into the engine body. This kind of cooler is a parallel arrangement of many thin-walled heat exchange copper tubes in the tube shell. The water flows through the copper tube and the hot oil or hot air flows through the copper tube. After heat exchange, the water takes away the heat of oil and air.