Comparison of scroll compressor and rolling rotor compressor

With the development of society, human beings have higher and higher requirements for the comfort of the living environment. Therefore, improving the compression efficiency and working reliability of the compressor, developing and applying material-saving and energy-saving compressors have become one of the main directions for the development of refrigeration technology. , The third-generation refrigeration and air-conditioning compressors---scroll compressors came into being and are widely used in this context, and replaced the traditional first and second-generation compressors in numerous commercial air-conditioning systems. While occupying a dominant position, rolling rotor compressors (second-generation compressors) still occupy a dominant position in small-capacity (below 3HP) air-conditioning units due to their relatively low manufacturing costs and relatively high performance. This article compares the specific application and related performance of scroll compressors and rolling rotor compressors in air conditioning technology.

The scroll compressor is a kind of compressor that increases the pressure by reducing the volume of the gas. It is a fluid machine that realizes gas compression by the change of volume. This is the same as the reciprocating compressor; scroll compression The machine changes the compressor volume through the rotation of the main shaft to drive the working rotor to move to achieve the purpose of suction, compression and exhaust. The movement of its main component, the movable scroll, is carried out under the direct drive of the eccentric shaft. It is the same as the rotary compressor; but the compression chamber of the scroll compressor is different from the reciprocating type and the rotary type, so it is called the new generation positive displacement compressor, that is, the third generation compressor. The type compressor has a very high efficiency, which is about 5% higher than the second-generation compressor rotor compressor.

The main components in the scroll compressor are two involute scrolls with the same shape but with a relative offset of 180° in angular position. One is a fixed scroll, and the other is driven by an eccentric shaft with its axis around An orbiting scroll in which the axis of the fixed scroll revolves. During work, the two scrolls are tangent to each other to form a sealing line, and the end faces of the two scrolls are properly sealed to form a tooth-shaped air cavity for several months. The sealing line at the common tangent point between the two scrolls continuously shifts along the vortex curve with the revolution of the orbiting scroll, so that the shape and size of these crescent-shaped air chambers are constantly changing. The suction port of the compressor is opened in the upper part of the fixed scroll shell. When the eccentric shaft rotates clockwise, air enters the suction cavity from the suction port, and is successively taken into the peripheral crescent-shaped air cavity communicating with the suction cavity. As these peripheral crescent-shaped air chambers are closed and no longer communicate with the suction chamber, their enclosed volume is gradually transferred to the center of the fixed scroll and shrinks continuously, the gas is continuously compressed and the pressure increases.

  From the specific structure, the scroll compressor has no suction and discharge valves, which greatly improves the reliability of high-speed operation.

   Taken together, scroll compressors have the following main features:

⑴. It belongs to the third-generation compressor. Multiple compression chambers work at the same time. The gas pressure difference between adjacent compression chambers is small, the gas leakage is small, and the volumetric efficiency is high, up to 98%, which is more compressed than the second-generation compressor rotor Machine efficiency is about 5% higher;

  ⑵, the eccentric shaft that drives the moving scroll can rotate at a high speed, so the scroll compressor is small in size and light in weight;

   (3) The force changes of moving parts such as the movable scroll and the main shaft are small, and the vibration of the whole machine is small;

  ⑷, there is no suction and exhaust valve, the scroll compressor runs reliably, and it is especially suitable for variable speed movement and frequency conversion speed regulation technology;

⑸ The compression chamber of the scroll compressor is composed of a scroll profile, which is a multi-chamber compression mechanism. When the center of the movable scroll moves in a circular motion around the center of the fixed scroll, the volume of each compression chamber changes with the rotation angle of the main shaft. Correspondingly reduce or expand, thereby realizing the gas suction, compression and exhaust process. Since the suction and exhaust process is almost continuous, the noise of the whole machine is very low;

⑹. The axial and radial flexible structure improves the production efficiency of the scroll compressor, and ensures that the sealing effect of the axial and radial gaps is not reduced due to friction and wear, that is, the scroll compressor is reliable and effective Sealability, so its refrigeration coefficient does not decrease with the increase of operating time, but slightly increases;

⑺. The scroll compressor has good working characteristics. Its performance is mainly affected by its own compression ratio and suction pressure. It has a wide range of discharge pressure and is suitable for various indoor and outdoor environments to ensure that the compressor is always running at a high energy efficiency ratio. So as to ensure the energy efficiency ratio of the air conditioning unit.

  In the heat pump air conditioning system, it is especially manifested in high heating performance, good stability and high safety;

⑻. The scroll compressor has no clearance volume. It belongs to multi-chamber compression in structure. The pressure difference between adjacent chambers is not very large (approximately continuous change). At the same time, the sealing strips at the contact parts of the moving and static scrolls are on the shaft The back pressure is compressed so that the moving and static scrolls are in close contact, and a good sealing effect is achieved with the help of refrigerating oil, so that internal leakage is almost non-existent; when the end plane of the sealing strip is worn, it can be axially The direction is automatically compensated to ensure that the end surface of the movable scroll and the bottom surface of the fixed scroll are always close, and the longer the compressor works, the better the cooperation of these close relative moving surfaces and the better the sealing effect. These advantages make the scroll The compressor does not have the problem of secondary compression of refrigerant gas, which is one of the important guarantee factors for maintaining high volumetric efficiency operation;

  ⑼, small torque change, high balance, small vibration, stable operation, easy operation and easy automation;

  ⑽. Because of its own few moving parts and no reciprocating mechanism, it has a simple structure, small size, light weight, few parts (especially few wearing parts), high reliability, and a life span of more than 20 years.