Disassembly and failure analysis of scroll compressor

Disassembly and failure analysis of scroll compressor The scroll compressor is a positive displacement compression compressor, and the compression component is composed of a movable scroll and a static scroll. This includes many structural features that divert the flow of gas through the compressor housing to reduce entrained oil. Working principle: The vortex shape of the vortex stator and the vortex rotor is basically the same, the phase difference is 180 °, and it has a certain eccentricity. Four compression chambers are formed between the two vortices, and each compression chamber has a crescent shape. During the compression process, the vortex stator (stationary disk) remains fixed, and the vortex rotor (moving disk) moves clockwise in a circle every 90 °. The gas in the air cavity is compressed into high-pressure gas and passes through the middle of the vortex Exhaust port. Disassemble the scroll compressor: 1.First disassemble the scroll machine from the air conditioning unit: 2.Cut the shell of the scroll machine with a cutting machine: 3、 3. Take out the rotor to see the motor coil: 3.Dismantle the high and low pressure separation cover: 4. Dismantle the high and low pressure separation cover: 5. Moving scroll: 6. Static scroll: The main performance of scroll compressor failure: The floating sealing ring is damaged, resulting in high and low pressure gas: the failure phenomenon generally shows that the compressor motor is intact and can be energized to run, but the exhaust pressure of the unit does not increase, the suction pressure does not decrease, and there is almost no suction and exhaust The pressure difference, the exhaust pipe is not hot, and the suction pipe is not cold. Scroll disk damage: Generally, it can be seen that the obvious metal impact sound inside the compressor can be heard. This is the sound of the metal fragments crushed by the scroll disk colliding with each other or the compressor casing. The motor is holding the shaft, and the bearing damage is mainly manifested in: the system does not have freezing oil, which causes mechanical wear in the compressor, exacerbates the generation of high heat, and cannot be dissipated very much to cause the shaft and the cylinder to jam. Causes and analysis of scroll compressor failure: The partial melting and breaking of the seal ring is a common failure phenomenon of scroll compressors. The reason is: due to refrigerant leakage, the suction pressure is reduced, and the suction superheat is increased, which causes the exhaust temperature to rise rapidly, which will cause serious overheating in the system. The most effective way to avoid thermal damage to the seals is to properly install the exhaust temperature protector. Scroll disk damage is generally caused by liquid impact, there are three main cases: ① A large amount of refrigerant liquid enters the compressor when starting up; ② The water flow of the evaporator is not enough (the evaporation load is reduced), and the compressor has liquid back phenomenon; ③ The defrosting of the heat pump of the unit is not good. A large amount of liquid refrigerant enters the compressor without evaporation, or the liquid in the four-way valve reversing instant evaporator (the condenser is the heat pump during operation) enters the compressor. The burning of the motor winding is related to the protection of the electrical design, or it is caused by the improper operation of the unit, which is divided into the following situations: ① Abnormal load. ② If the electrical design does not have overload protection or overcurrent protection, it may be dangerous. ③ Frequent start and stop of the motor will make the contactors of poor quality easily stick together. ④ Insufficient cooling is also one of the causes of compressor motor burnout. When the motor holds the shaft, the root cause of bearing damage is lubrication. Can be divided into the following situations: ① There is not enough lubricating oil, or there is a problem with the oil return from the system. ② There are impurities in the system entering the bearing, the bearing is worn or stuck, causing the motor to hold the shaft. ③ There is no pre-heating or insufficient pre-heating time before starting up, which causes a large amount of refrigerant in the system to migrate to the compressor. Once the fully enclosed scroll compressor is damaged, it is almost impossible to repair, and the compressor can only be replaced. The resulting loss is relatively large. It is very important to take appropriate precautions in operation.

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