Scroll air compressor ---- belongs to the volumetric rotary machinery, the use of scroll rotor and scroll stator engagement formed a number of compression chamber. With the translational rotation of the scroll rotor, the volume inside the compression chamber is constantly changing to realize the suction and compression of the gas.
The working principle of scroll compressor
The main components of the compressor are two involute scrolls with the same shape but with the angular position staggered by 180°, one of them is a fixed scroll, and the other one is driven by the eccentric shaft, and its axis rotates around the axis of the fixed scroll to make a revolution of the winding scroll. In operation, the two coils form a sealing line tangent to each other in many places, together with proper sealing at the end faces of the two coils, thus forming several crescent-shaped air chambers. The sealing line at the male **** tangent point between the two coils is continuously shifted along the vortex curve with the rotation of the winding coil, so that the shape and size of these crescent-shaped cavities are always changing. The suction port of the compressor opens in the upper part of the fixed coil housing. 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 cavities that are connected to the suction chamber. With the closure of these peripheral crescent-shaped cavities and not connected to the suction chamber, the confined volume will gradually be transferred to the center of the fixed volume and constantly shrinking, the gas is constantly compressed and the pressure rises.
What are the characteristics of scroll compressors?
Advantages:
1, there is no reciprocating mechanism, so the structure is simple, small size, light weight, few parts (especially less wearing parts), high reliability;
2, small torque changes, high balance, low vibration, smooth operation, thus easy to operate, easy to realize automation;
3, in the refrigerant capacity of the range of its adaptation has a high Efficiency; 4, low noise
Disadvantages: 1, the surface of the moving parts are curved shapes, the processing of these surfaces and their inspection are more complex, and some also need special equipment, so the manufacturing cost is higher.
2, between the moving parts or moving parts and fixed parts, often to maintain a certain movement gap to achieve sealing, the gas through the gap is bound to cause leakage, which restricts the rotary compressor is difficult to achieve a larger compression ratio, therefore, more in the air conditioning conditions.
Screw compressor --- is also a rotary volumetric machinery, the compression of air by the device in the casing of the parallel meshing with each other, the yin and yang rotor teeth groove of the volume changes to achieve.
Screw compressor principle
Screw compressor cylinder is equipped with a pair of mutually meshing spiral yin and yang rotors, both rotors have several concave teeth, both rotating in the opposite direction. The clearance between the rotors and between the casing and the rotors
is only 5 to 10 filaments, the main rotor (also known as the yang rotor or convex rotor), driven by the engine or motor (most of them are driven by the electric motor), and the other rotor (also known as the yin rotor or concave rotor) is driven by the main rotor through the oil film formed by the oil injection, or by the synchronous gears at the end of the main rotor and the end of the concave rotor drive. So there is no metal contact in the drive (theoretically). The length and diameter of the rotor determines the compressor discharge (flow) and discharge pressure, the longer the rotor, the higher the pressure; the larger the rotor diameter, the higher the flow.
The spiral rotor groove is filled with gas as it passes through the suction port. When the rotor rotates, the rotor groove is closed by the housing wall, forming a compression chamber, when the rotor groove is closed, the lubricant is sprayed into the compression chamber, sealing. Cooling and lubrication. When the rotor rotates to compress the lubricant + gas (referred to as oil-gas mixture), the compression chamber volume decreases, and the oil-gas mixture is compressed to the exhaust port. When the compression chamber passes through the exhaust port, the oil and gas mixture is discharged from the compressor, completing a suction - compression - exhaust process. Each rotor of a screw machine is supported by a friction-reducing bearing, which is held in place by an end cap near the end of the rotor shaft. The inlet end is supported by roller bearings, and the exhaust end is supported by a pair of he tapered roller bearings usually at the exhaust end to position the rotor, that is, thrust bearings, to resist axial thrust, to withstand radial loads, and to provide the minimum clearance necessary for axial operation.
The operating cycle can be divided into three processes: suction, compression and exhaust. As the rotor rotates, each pair of intermeshing teeth successively completes the same work cycle.
The advantages of screw compressors:
1) Screw compressors are the same as piston compressors, both belong to the volumetric compressor. Screw air compressor has the following advantages in terms of the use of the effect.
2) high reliability. Screw compressor parts less, no wearing parts, so it runs reliably, long life, overhaul intervals up to 4-8 million hours.
3) easy to operate and maintain. Screw compressor high degree of automation, the operator does not have to go through a long period of professional training, can be realized unattended operation.
4) good power balance. Screw compressor is not unbalanced inertia force, the machine can work smoothly at high speeds, can realize the foundation of the operation, especially suitable for mobile compressor, small size, light weight, covers an area of less.
5) adaptable. Screw compressor has the characteristics of forced gas transmission, volumetric flow is almost unaffected by the exhaust pressure, in a wide range to maintain high efficiency, in the compressor structure does not make any changes in the case of a variety of working conditions.
Disadvantages of screw compressor
1) rotor tooth surface is a space surface, need to utilize special tools, in the expensive equipment processing, body parts processing accuracy also has high requirements, must use high-precision equipment:
2) due to the inter-tooth volume periodically connected with the suction and discharge ports, so the compressor noise is relatively high;
3) due to the rotor stiffness and bearing life and other limitations, the compressor can only rely on internal gap sealing, so the screw compressor can only be applied to the medium and low pressure range, can not be used for high-pressure occasions;
4) due to the large amount of oil spraying, oil treatment system is complex, so the set of ancillary equipment;
5) screw compressor relies on the gap sealing gas rest, in the small volume range does not have superior Performance.
In short. Screw compressor with its significant advantages, more and more recognized by the market. With the development of the national economy, as well as screw compressor design, manufacturing level. Screw compressor performance indicators and reliability indicators will be more improved. Screw compressor market will become more and more extensive.