The principle of air-conditioning compressor

The principle of air-conditioning compressor Abstract: The air-conditioning compressor plays the role of compressing and driving the refrigerant in the air-conditioning refrigerant circuit. Air-conditioning compressors are generally installed in outdoor units. What is the principle of air-conditioning compressor? What is the reason why the air conditioner compressor does not start? How to replace the air conditioner compressor? The compressor is the heart of the refrigeration system of the air conditioner. The refrigerant circulation or flow in the system is achieved by the operation of the compressor. Once the compressor stops, cooling is over. The compressor compresses the refrigerant as Abstract: The air-conditioning compressor plays the role of compressing and driving the refrigerant in the air-conditioning refrigerant circuit. Air-conditioning compressors are generally installed in outdoor units. What is the principle of air-conditioning compressor? What is the reason why the air conditioner compressor does not start? How to replace the air conditioner compressor? The compressor is the heart of the refrigeration system of the compressor. The refrigerant circulation or flow in the system is realized by the operation of the compressor. Once the compressor stops, cooling is over. The process of compressing the refrigerant by the compressor is that the compressor sucks the evaporated saturated gas from the evaporator, increases its pressure and temperature through compression, and then discharges it into the condenser for condensation. 1. Classification and principle of air conditioner compressor At present, air conditioner compressors can be roughly divided into the following five types. 1. Piston compressor The application of piston compressors is earlier, the power is relatively large, and the temperature resistance of the motor coil is not very high, so most domestic and foreign cabinet air conditioners use this type of compressor. Its shortcomings are large volume, complex structure, low efficiency, relatively large noise and vibration, and will be gradually eliminated. Its structure is shown in the following figure (a). 2. Rotary piston compressor The rotary piston compressor has a simple structure, small volume, light weight, and few parts. It is 60% smaller in volume, 35% in weight, and 50% in parts than a reciprocating piston compressor with the same cooling capacity. This compressor only performs rotary motion and does not need to convert rotary motion into reciprocating motion of the piston, so the operation is stable, the vibration is small, and the noise is low. Since the suction and discharge of the rotary compressor are continuous, no suction valve is required. In order to prevent high-pressure gas from returning to the cylinder after shutdown, only an exhaust valve is provided. Because there is no suction valve, the loss of suction pressure is reduced, and the volumetric efficiency and energy efficiency ratio are increased, but the machining accuracy of the parts is very high, and the life is shorter than that of the piston compressor. This type of compressor has only one rotor and is eccentrically arranged, so the vibration is large when rotating, so a dual-rotor rotary compressor appears, and the two rotors of the compressor are symmetrically distributed, so the dynamic balance is improved. Its structure is shown in figure (b) below. 3. Rotary vane compressor The characteristics of the sliding vane compressor are basically the same as the piston compressor, except that its friction power is high, the speed of the compressor is low when the compressor is started, and the centrifugal force is small, and a good seal cannot be formed. But its start-up performance is better. In order to prevent the motor from overheating, the compressor is equipped with a precooler circuit. The disadvantage is that the compressor has a total of four outlet pipes, the structure is slightly more complicated, and a certain cooling capacity will be lost, so the efficiency is lower. 4. Scroll compressor Compared with the reciprocating piston compressor, it has the characteristics of 40% smaller volume, 15% lighter weight, 10% higher efficiency, and lower noise. There are only 5 main parts. The reciprocating piston compressor has more than 30 main components, and the scroll compressor does not have an intake valve and an exhaust valve. The torque change during operation is small, and the overall performance is better than the piston rotary compressor, but the processing accuracy is high and the shape Complicated, service life is not as good as piston reciprocating compressor. Its structure is shown in figure (c) below. 5. Inverter compressor It is different from general compressors, which can run at high and low speeds arbitrarily, so that the compressor displacement can be effectively changed and controlled. Most of these compressors use scroll type, double rotor type, and some also use reciprocating compressors. The motor coil is three-phase and the frequency adjustable range is 30 ~ 130Hz. Compressor requirements for motor coils. The working environment of the air conditioner compressor is relatively harsh, so the motor coil is required to have strong overload capacity, heat resistance, and large starting torque to avoid compressor damage when the power supply voltage is low. The lead wire of the compressor coil must be resistant to oil and fluorine. In addition, it must be resistant to vibration, shock, high efficiency, light weight and small size. It can start and run normally within 10% of the rated voltage. The coil winding is basically the same as the general motor winding. The winding coil uses fluorine-resistant insulated electromagnetic wire and other fluorine-resistant insulating materials. 2. What's wrong with the air-conditioning compressor not starting? The compressor will continue to work after the air conditioner is turned on to achieve the regulated temperature, but many friends report that the compressor of the air conditioner at home does not work at all. Why? One reason why the air conditioner compressor does not start: The general situation is caused by long-term operation under insufficient Freon. Due to improper installation, internal leakage in the system is the root cause of insufficient refrigerant. Solution: add freon to the air conditioner. The second reason why the air conditioner compressor does not start:

During installation, the air in the system was not exhausted, there was ice blocking phenomenon, and the compressor load increased. The increase in compressor load causes the compressor temperature to increase, and the refrigeration oil will deteriorate for a long time at high temperature. It will not be able to lubricate and reduce the temperature, which will cause the compressor temperature to rise further. The coil will be damaged due to the reduction of high-temperature insulation. Solution: strictly control the quality during installation. Three reasons why the air conditioner compressor does not start: The power supply is not connected or there is no power, the power wire socket has poor contact, or the power wire diameter is thin or aging, and the power supply voltage is low. Starting frequency of fixed frequency air conditioner: 187V, voltage fluctuation range: 198-242V, starting frequency of inverter air conditioner 156V, voltage fluctuation range: 176-264V, it is recommended that the family install the regulator because the connecting pipe is bent and the compressor is installed during installation The workload increases. Solution: Check whether the power cord is aging. Four reasons why the air conditioner compressor does not start: Function lock protection. Some brands or models have a child lock function. If you are in lock mode and cannot perform any operation, you can cancel it by referring to the manual. The compressor is operated at high temperature for a long time, resulting in reduced insulation, low coil resistance, increased starting current, and compressor The temperature rises instantly. Solution: Follow the instructions to unlock. Five reasons why the air conditioner compressor does not start: Electric wire fault, solution: check and repair, the differential pressure relay is disconnected, the high-voltage disconnector is disconnected, press the reset button of the differential pressure relay and wait for the pressure change to close the contact or readjust the opening pressure. 3. Air conditioner compressor replacement It is not difficult to replace the press, pay attention to the following points: ⑴The maintenance is safe. Please pay attention to the following two lovely maintenance brothers: 1. Although the refrigerant (R22) in the air conditioner is not a probable gas, it will decompose and produce toxic gas if it comes into direct contact with a high-temperature flame! 2. Before the welding operation, slowly release the refrigerant in the refrigeration system. If the pressure in the refrigeration system is too high, the welding operation is very dangerous. At this time, the welding operation must not be performed. ⑵ Judgment status The condition of the refrigeration system is normal and the condition of abnormal oil is light yellowish brown: the freezing oil has deteriorated, and the high temperature causes black: abrasion or the freezing oil is severely carbonized yellow-green: there is moisture in it which produces acidic smell and no barbecue smell is irritating (3) When the residual refrigerant is discharged, it must be slowly discharged, and the lubricant in the compressor will be discharged too quickly. If the compressor is burned out, it will release the toxic gas generated when the refrigerant is thermally decomposed. Please pay attention to the operator. ⑷After discharging the refrigerant, remove the electrical plug and parts on the compressor. ⑸. Remove the welding parts of the high and low pressure connecting pipes (in order to prevent the sound insulation material from being burned, a protective layer can be used). ⑹. Remove the old compressor. ⑺Check out the oil color of the compressor refrigeration oil. If the oil color is abnormal, the system should be cleaned. ⑻. Install a new compressor. ⑼Bend and shape the high and low pressure connecting pipe with a pipe bender, and install the original rubber feet. ⑽ Brazing operation, brazing the pipe joint. ⑾Connect the compressor wire. In order to avoid the wiring error of the terminal terminal, the wiring must refer to the circuit diagram. ⑿ The system is evacuated. Sufficient suction time is required to ensure the vacuum of the system. ⒀ Fluorine filling, leak detection. Charge the fluoride according to the standard fluoride charge on the nameplate. When replacing the scroll compressor, the high-pressure side and the low-pressure side must be carried out at the same time when discharging the refrigerant. It is forbidden to perform only from the high-pressure side. The axial seal of the scroll disk will cause the refrigerant to remain on the low-pressure side. During the welding operation, in order not to cause an oxide film to form on the inner wall of the copper pipe, nitrogen must be passed in. The time for the nitrogen to pass should be sufficient. The inspection method is to place a lit incense or cigarette end at the other outlet of the nitrogen. The air in the system is evacuated, and then the welding operation can be performed. Due to the high requirements for the use of scroll compressors, it is forbidden to use the compressor as a vacuum pump to evacuate the air in the pipeline of the external machine when replacing the compressor or other parts, otherwise the compressor will be burned, and the vacuum pump must be used to evacuate. When the system is receiving gas during maintenance, it is not allowed to reduce the pressure in the system to a vacuum state, only the pressure in the system can be maintained above 0.03MP gauge pressure, otherwise it will cause the compressor suction side scroll disk to form an axial seal to form a vacuum , Improper operation will damage the compressor.

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