Strategy丨Common failures and maintenance of piston refrigeration compressors

Strategy丨Common failures and maintenance of piston refrigeration compressors

1. The refrigeration compressor cannot start normally

　　Overhaul ideas

　　 1. Firstly, check whether it is caused by low power supply voltage or poor motor circuit connection. If it is indeed that the grid voltage is too low, restart after the grid voltage returns to normal: If the line is in poor contact, the connection between the line and the motor should be detected and repaired.

　　2. Check whether the exhaust valve plate is leaking: If the exhaust valve plate is damaged or the seal is not tightly leaked, the pressure in the crankcase will be too high, resulting in failure to start normally. Just replace the exhaust valve plate and sealing line.

　　 3. Check whether the energy adjustment mechanism is out of order. Mainly check whether the oil supply pipeline is blocked, the pressure is too low, and the oil piston is stuck, and repair it according to the cause of the failure.

　　 4. Check whether the temperature controller is damaged or out of adjustment; if it is out of adjustment, the temperature controller should be adjusted; if it is damaged, it should be repaired or replaced.

　　 5. Check whether the pressure relay is malfunctioning. Check the pressure relay and reset the pressure parameters.

　　 2. No oil pressure

　　 1. Check whether there is oil leakage or blockage at the connection of the oil pump piping system. The joint should be tightened; if it is blocked, the oil pipeline should be cleared.

　　2. Is the oil pressure regulating valve opened too large or the valve core falls off? If the oil pressure regulating valve is improperly adjusted, the oil pressure regulating valve should be adjusted and the oil pressure should be adjusted to the required value; if the spool falls off, the spool should be reinstalled and tightened firmly.

　　3. If there is too little oil in the crankcase or there is refrigerant, the oil pump will not enter oil. If there is too little oil, refuel in time; if it is the latter, stop the machine in time to remove the refrigerant.

　　4. The oil pump is severely worn. The gap is too large, causing the oil pressure to fail. In this case, the oil pump should be repaired and replaced directly when the fault is serious.

　　 5. Check whether the connecting rod bearing, main bearing bush, connecting rod small end bushing and piston pin have been severely worn. At this time, relevant parts should be replaced in time.

　　6. ​​The gasket of the crankcase rear end cover is misaligned, which blocks the oil inlet channel of the oil pump. It should be disassembled and checked, and the gasket position should be fixed again.

　　 Three, a large amount of foam is generated in the crankcase

　　Overhaul ideas

　　 The lubricating oil in the crankcase foamed and the liquid hit was caused by the following two reasons:

　　 1. There is a large amount of refrigerant mixed in the lubricating oil. When the pressure drops, the refrigerant will evaporate and produce a lot of foam. In this regard, the refrigerant in the crankcase should be evacuated.

2. Too much lubricating oil is added to the crankcase, and the big end of the connecting rod stirs the lubricating oil, causing a lot of foam. For this, the excessive lubricating oil in the crankcase should be released to make the oil level reach the specified oil level. .

　　 Fourth, the oil temperature is too high

　　Overhaul ideas

　　 1. The shaft and the bush are not properly assembled. The clearance is too small. The size of the assembly gap between the shaft and the bush should be adjusted to make the gap meet the standard requirements.

　　2. The lubricating oil contains impurities, which leads to the bearing bushing. In this regard, you should scrape the brushed bearing bush flat and replace it with new oil: if the tile is severely brushed, replace with a new tile.

　　 3. The shaft seal friction ring is installed too tightly or the friction ring is rough. The shaft seal friction ring should be re-adjusted. If the friction ring is severely roughed, replace it with a new one.

　　4. If it is caused by the excessively high temperature of the suction and discharge of the compressor, the liquid supply valve of the system should be adjusted appropriately to restore the suction and discharge temperature to normal.

　　 5. The pressure in the crankcase increases

　　 1. The piston ring is not tightly sealed, which leads to high pressure to low pressure. The new piston seal ring i should be replaced.

　　2. The exhaust valve is not closed tightly, causing the pressure in the crankcase to rise. The sealing of the exhaust valve seat should be checked. If the sealing is not tight, the new valve should be replaced in time.

　　3. The tightness of the cylinder liner and the machine base becomes poor: the cylinder liner should be removed, the joints should be cleaned and sealed, and then reassembled.

　　4. Too much refrigerant enters the crankcase, and the pressure rises after evaporation: Just evacuate the excessive refrigerant in the crankcase.

　　 Six, energy regulation mechanism malfunction

　　 1. Check if the oil pressure is too low or the oil pipe is blocked. If the oil pressure is too low. Adjust and increase the oil pressure; if the oil pipe is blocked, the oil pipe should be cleaned and unblocked.

　　2. Is the oil piston jammed? Remove the oil piston to clean and replace the dirty oil. Reassemble it correctly.

　　 3. Whether the tie rod and the rotating ring are installed incorrectly, causing the rotating ring to be jammed-focus on checking the assembly of the tie rod and the rotating ring, and repair it until the rotating ring can rotate flexibly.

　　 4. Check whether it is caused by improper assembly of the oil distribution valve. If the ventilation method is used to check whether each working position is appropriate, and then adjust the oil distribution valve.

　　 Seven, the return air heat is too large

　　Overhaul ideas

　　 1. Check whether the ammonia in the evaporator is too small or the opening of the liquid supply valve is too small. If the system is lack of ammonia, it should be replenished in time; if the liquid supply valve is not adjusted properly, the liquid supply valve should be opened to the appropriate position.

　　2. Is it because the insulation layer of the return air pipe is poorly insulated or damaged by moisture? The insulation layer should be checked thoroughly and replaced with new insulation materials.

　　3. The suction valve is leaking or ruptured and damaged: If the leakage is slight, the valve can be ground to make it no longer leaking; if it is broken, replace the suction valve directly.

　　 8. No oil pressure

　　Overhaul ideas

　　 1. Check whether there is oil leakage or blockage at the connection of the oil pump piping system. The joint should be tightened; if it is blocked, the oil pipeline should be cleared.

　　2. Is the oil pressure regulating valve opened too large or the valve core falls off? If the oil pressure regulating valve is improperly adjusted, the oil pressure regulating valve should be adjusted and the oil pressure should be adjusted to the required value; if the spool falls off, the spool should be reinstalled and tightened firmly.

　　3. If there is too little oil in the crankcase or there is refrigerant, the oil pump will not enter oil. If there is too little oil, it should be refueled in time; if it is the latter, it should be shut down in time to remove ammonia.

　　4. The oil pump is severely worn. The gap is too large, causing the oil pressure to fail. In this case, the oil pump should be repaired and replaced directly when the fault is serious.

　　 5. Check whether the connecting rod bearing, main bearing bush, connecting rod small end bushing and piston pin have been severely worn. At this time, relevant parts should be replaced in time.

　　6. The gasket of the crankcase rear end cover is misaligned, which blocks the oil inlet channel of the oil pump. It should be disassembled and checked, and the gasket position should be fixed again.

　　 Nine, the compressor suction pressure is lower than the normal evaporation pressure

　　Overhaul ideas

　　1. The opening of the liquid supply valve is too small, which can lead to insufficient liquid supply, so the evaporation pressure will drop. For this, just open the liquid supply valve to an appropriate level.

　　2. The valve in the suction line is not fully opened or the valve core is off. If it is the former, the valve should be fully opened; if the valve core falls off, the valve core should be reinstalled.

　　 3. There is a lack of refrigerant in the system, even if the pressure valve is opened, the evaporation pressure is still low. At this time, the appropriate amount of refrigerant should be added according to the actual situation.

4. The return air pipeline is thin, or there is a "liquid sac" phenomenon in the return air pipeline. If the pipe diameter is too small, a suitable return air pipe should be replaced; if there is a "liquid sac" phenomenon, the return air pipeline should be Remove the "liquid sac" section and re-weld the pipe.

　　 10. Compressor wet stroke

　　Overhaul ideas

　　1. When the compressor is started, if the suction valve is opened too fast, it will cause wet stroke: Therefore, the suction valve should be opened slowly when starting to avoid wet stroke and damage to the compressor.

　　2. If the opening of the liquid supply valve is too large, it will also cause a wet stroke. At this time, just close the liquid supply valve appropriately.

　　3. When the cold storage returns to normal temperature after defrosting, slowly open the suction valve and observe the operation of the refrigeration compressor at any time. If the return air temperature drops too fast, you should temporarily stop the opening, and when the operation returns to normal, continue to open slowly.

　　11, there is a knocking sound in the crankcase

　　Overhaul ideas

　　 1. Check whether the gap between the connecting rod head bush and the shaft journal is too large. At this time, the gap should be adjusted or replaced with new tiles directly.

　　2. If the gap between the main bearing and the main journal is too large, collision and friction will occur, resulting in knocking sound. New tiles should be repaired or replaced.

　　 3. Check whether the split pin is broken and the connecting rod nut is loose. If it is, replace the cotter pin with a new one and tighten the connecting rod nut.

　　4. If the center of the coupling is not right or the keyway of the coupling is loose. Should adjust the coupling or repair the keyway or replace the new key.

　　 5. The main bearing steel ball is worn and the bearing frame is broken. For this, just replace the new bearing.

　　12, the shaft seal leaks seriously

　　Overhaul ideas

　　 1. Check whether the shaft seal is poorly matched, causing serious oil leakage in the shaft seal. The shaft seal should be assembled correctly.

　　2. Check whether the friction surface between the moving ring and the fixed ring has been roughened. If the fuzz is severe, the sealing surface should be carefully ground and reassembled.

　　3. If the rubber sealing garden is aging or the tightness is not set properly, oil will leak: For this, the rubber garden should be replaced with a new one and the appropriate tightness should be adjusted.

　　4. Check whether it is due to the weakening of the elastic force of the shaft seal spring that the shaft seal leaks oil: the original spring should be removed and replaced with a new one of the same size.

　　 5. Check whether the sealing performance of the back of the fixing ring and the shaft seal gland has deteriorated. In this regard, remove the fixing ring, clean the back ring and reassemble it.

　　 6. If the crankcase pressure is too high, adjustments should be made. But before stopping, lower the pressure of the crankcase and check whether the exhaust valve leaks.

　　13, the cylinder wall temperature is overheated

　　Overhaul ideas

　　 1. If the oil pump fails, which causes the oil pressure to be too low or the oil circuit is blocked: shut down for a full overhaul.

　　 2. Check whether the gap between the piston and the cylinder wall is too small or the piston is off-track: At this time, the piston should be adjusted.

　　 3. The safety block or false cover is not tightly sealed, resulting in high and low pressure gas leakage. In this regard, measures should be taken to repair and improve the sealing performance.

　　 4. Check whether the suction temperature is too high. Adjustments should be made to lower the suction temperature.

　　 5. If the quality of lubricating oil is not good, the viscosity is too small. Stop the machine and replace with new lubricating oil.

　　6. ​​Check whether the scale in the cooling water jacket is too thick or the amount of water is insufficient: if the scale is too thick, it should be removed in time; if the amount of bitter water is insufficient, the amount of cooling water should be increased.

　　 7. Check whether the suction and exhaust valves are damaged. If damaged, replace the suction and exhaust valves in time.

　　 8. Check whether the piston ring is severely worn. If yes, replace with a new piston.