Disassembly and Fault Analysis of Scroll Compressor

The scroll compressor is a volumetric compression compressor, and the compression member is composed of an orbiting scroll and a stationary scroll. A shunt flow of gas through the compressor housing is included to reduce many of the structural features of the entrained oil.

Working principle: The scroll shape of the scroll stator and the vortex rotor are basically the same, the phase difference is 180°, and has a certain eccentricity. Four compression chambers are formed between the scroll 2, each of the crescent-shaped compression chambers were tested.

During the compression process, the scroll stator (static disc) remains fixed, while the vortex rotor (moving disc) moves clockwise every 90° , and the gas in the air chamber is compressed into high pressure gas and vortexed in the middle. The exhaust port is exhausted.

Dismantle the scroll compressor:

1. First disassemble the scroll machine from the air conditioning unit:

2. Cut the scroll casing with a cutter:

3. Take out the rotor and you can see the motor coil:

4 , dismantling the high and low pressure divider cover:

5 , moving scroll:

6 , static scroll:

The main performance of the scroll compressor is fault:

The floating seal is damaged, causing high and low pressure gas: the fault phenomenon is generally characterized by the compressor motor being in good condition and capable of running on electricity, but the exhaust pressure of the unit is not increased, the suction pressure is not lowered, and the suction and exhaust are almost no The pressure difference, the exhaust pipe is not hot, and the suction pipe is not cool.

Corrugated disk damage: Generally speaking, it can hear the obvious metal impact sound inside the compressor. This is the sound of the metal fragments after the scroll is crushed or collided with the compressor casing.

Motor holding shaft, bearing damage is mainly manifested in: the system has no refrigeration oil , causing mechanical wear inside the compressor, exacerbating the generation of high heat, can not be very open and dissipated, resulting in the holding shaft, card cylinder

Causes and analysis of scroll compressor failure:

Partial melting and fracture of the seal ring is a common failure phenomenon of scroll compressors. The reason is that due to refrigerant leakage, the suction pressure is lowered, and the suction superheat is increased, causing the exhaust gas temperature to rise rapidly, which may cause serious overheating of the system. An effective way to avoid thermal damage to the seal is to properly install the exhaust temperature protector.

Scroll damage is generally caused by liquid hammer, there are three main cases :

1 At the moment of starting up, a large amount of refrigerant liquid enters the compressor;

2 The evaporator water flow is not enough (the evaporation load is reduced ) , and the compressor has a liquid return phenomenon;

3 unit heat pump operation is not good for defrosting, a large amount of liquid refrigerant does not evaporate into the compressor, or the four-way valve reversing the instantaneous evaporator (the condenser when the heat pump is running ) into the compressor.

Motor winding burnout is related to the protection of electrical design, or caused by improper operation of the unit, divided into the following cases:

1 The load is abnormal.

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 contactor contact of poor quality easy to stick.

4 Insufficient cooling is also one of the causes of compressor motor burnout.

The fundamental reason for the motor to hold the shaft and the bearing is the lubrication problem. Can be divided into the following situations:

1 The oil is not enough, or there is a problem with the system returning oil.

2 There are impurities in the system into the bearing, the bearing is worn or stuck, causing the motor to hold the shaft.

3 There is no preheating or preheating time before starting, which causes a large amount of refrigerant in the system to migrate to the compressor.

Once the full-sealed scroll compressor is damaged, it can hardly be repaired, and only the compressor can be replaced. The resulting loss is relatively large. Therefore, how to deal with the common faults of the full-sealed scroll compressor should be designed. It is very important to take appropriate precautions in operation.

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