Comparison of Screw Compressor and Scroll Compressor

Scroll air compressor and screw air compressor are all volumetric rotary compressors. The scroll air compressor uses the meshing of the rotor and the stator to form a plurality of compression chambers. With the translation and rotation of the rotor, the volume of each compression chamber is constantly changing to realize the suction and compression of gas; while the screw air compressor compresses the air It is achieved by the volume change of the tooth grooves of the male and female rotors meshing in parallel in the casing.

Working principle of scroll air compressor

the main components in the scroll compressor are two involute scroll coils with the same shape but the angular phase position is relatively staggered by 180 °. One is a fixed coil, and the other is driven by an eccentric shaft, and its axis revolves around the axis of the fixed coil. In operation, the two coils are cut in multiple directions to form a sealing line, and the two coils are properly sealed at the end faces to form several crescent-shaped air cavities. The seal line at the common tangent point between the two rolls shifts continuously along the vortex curve as it revolves around the roll, causing the shape and size of these crescent-shaped air cavities to change all the time. The suction port of the compressor is opened on the upper part of the shell of the fixed coil body. When the eccentric shaft rotates clockwise, the gas enters the suction chamber from the suction port and is successively ingested into the peripheral crescent-shaped air chamber communicating with the suction chamber. With the closure of these peripheral crescent-shaped air chambers instead of communicating with the suction chamber, the sealed volume is gradually transferred to the center of the fixed coil body and is continuously reduced, the gas is constantly compressed and the pressure rises.

Working principle of scroll air compressor

working principle of screw air compressor

screw air compressor cylinder is equipped with a pair of intermeshing spiral male and female rotor, the two mutually reverse rotation. The gap between the rotors and between the casing and the rotor is only 5 to 10 wires. The main rotor is driven by the engine or electric motor, and the female rotor is driven by the oil film formed by the main rotor through oil injection, or by the main rotor end and the concave Rotor end synchronous gear drive. The spiral rotor groove is filled with gas when it passes through the suction port. When the rotor rotates, the rotor groove is closed by the casing wall to form a compression chamber. When the rotor groove is closed, the lubricating oil is injected into the compression chamber for sealing, Cooling and lubrication. When the rotor rotates to compress the lubricant oil-gas mixture, the volume of the compression chamber decreases and the oil-gas mixture is compressed to the exhaust port; when the compression chamber passes through the exhaust port, the oil-gas mixture is discharged from the compressor to complete an intake-compression-Exhaust process. Each rotor of the screw machine is supported by antifriction bearings, which are held by end caps near the ends of the shaft. The intake end is supported by a roller bearing, and the exhaust end is supported by an opposed cone roller. Usually, the exhaust end bearing positions the rotor, that is, the thrust bearing, which resists axial thrust and bears radial load. And provide the necessary minimum clearance for axial operation. The working cycle can be divided into three processes: suction, compression and exhaust. As the rotor rotates, each pair of intermeshing teeth successively completes the same duty cycle.

Working principle of screw air compressor

advantages of scroll air compressor

1. There is no reciprocating mechanism, so the structure is simple, small in size, light in weight, few parts (especially few wearing parts), and high reliability;

2. Small torque change, high balance, small vibration, stable operation, easy to operate and easy to realize automation;

3. It has high efficiency within the scope of its cooling capacity;

4. Low noise

advantages of screw air compressor

1. Screw compressors are the same as piston compressors and belong to positive displacement compressors. On the use of the effect to see the screw air compressor has the following advantages.

2. High reliability. Screw compressor parts less, no wearing parts, so it is reliable operation, long life, overhaul interval of up to 4-80000 hours.

3. Convenient operation and maintenance. The screw compressor has a high degree of automation, and the operator does not have to go through a long period of professional training, and can realize unattended operation.

4, the power balance is good. The screw compressor has no unbalanced inertial force, the machine can work smoothly at high speed, and can realize no-foundation operation. It is especially suitable for mobile compressors with small size, light weight and less floor space.

5, strong adaptability. The screw compressor has the characteristics of forced gas transmission, the volume flow is almost not affected by the exhaust pressure, and can maintain high efficiency in a wide range. It is suitable for a variety of working conditions without any change in the structure of the compressor.

Screw air compressor

disadvantages of scroll air compressor

1. The surface of the moving parts is mostly curved, and the processing and inspection of these curved surfaces are more complicated, and some require special equipment, so the manufacturing cost is higher.

2. Between the moving parts or between the moving parts and the fixed parts, a certain moving gap is often maintained to achieve sealing. The gas passing through the gap will inevitably cause leakage, which limits the difficulty of the rotary compressor to achieve a larger compression ratio. Therefore, it is mostly used under air-conditioning conditions.

Disadvantages of screw air compressor

1, the rotor tooth surface is a space surface, need to use a special tool, in the expensive equipment processing, the body parts processing accuracy also has higher requirements, must use high precision equipment:

2. Since the volume between teeth is periodically connected with the suction and exhaust ports, the compressor noise is relatively high;

3, due to the rotor stiffness and bearing life and other limitations, the compressor can only rely on the gap seal, so the screw compressor can only be applied to the low pressure range, can not be used for high pressure occasions;

4. Due to the large amount of oil injection and the complexity of the oil treatment system, there are many ancillary equipment of the unit;

5. The screw compressor relies on the gap seal and does not have superior performance in a small volume range.

Scroll air compressor

application of Scroll Air Compressor

scroll machine is mainly used in offices, hospitals, laboratories and so on some places with high noise and vibration requirements, it should be said that the scroll machine in the air compressor is a type of minimum noise and vibration. There is no energy saving. If you want to use a scroll machine, you are recommended to use Hitachi brand machines. Things are not cheap, but the quality is really good.

Application of Screw Air Compressor

screw type air compressor is widely used in machinery, metallurgy, electronic power, medicine, packaging, chemical industry, food, mining, textile, transportation and many other industrial fields, become the mainstream product of compressed air compressor.