What Should Be Done When These Problems Occur in the Semi-hermetic Piston Compressor of the Cold Storage?

2025-03-31

I. Maintenance Ideas for the Abnormal Start of the Refrigeration Compressor

First, check whether it is caused by too low a power supply voltage or poor connection of the motor circuit. If it is indeed due to too low a grid voltage, start it again after the grid voltage returns to normal. If there is a poor connection in the circuit, check the connections related to the motor in the circuit and repair them.
Check whether the discharge valve plate is leaking. If the discharge valve plate is damaged or not tightly sealed, it will cause the pressure in the crankcase to be too high, making it impossible to start normally. Just replace the discharge valve plate and the sealing line.
Check whether the energy adjustment mechanism is malfunctioning. Mainly check whether there are situations such as blockage in the oil supply pipeline, too low pressure, and the oil piston being stuck, and repair according to the cause of the failure.
Check whether the temperature controller is damaged or out of adjustment. If it is out of adjustment, adjust the temperature controller. If it is damaged, repair or replace it.
Check whether the pressure relay is malfunctioning. Overhaul the pressure relay and reset the pressure parameters.
II. Maintenance Ideas for the Absence of Oil Pressure
Check whether there are any oil leakage or blockage at the connection points of the oil pump pipeline system. If there is oil leakage, tighten the joint. If there is a blockage, dredge the oil pipeline.
Check whether it is due to the oil pressure regulating valve being opened too much or the valve core falling off. If the oil pressure regulating valve is improperly adjusted, adjust the oil pressure regulating valve and adjust the oil pressure to the required value. If the valve core has fallen off, reinstall the valve core and fasten it firmly.
If there is too little oil in the crankcase or there is refrigerant, it will cause the oil pump not to draw in oil. If there is too little oil, add oil in time. If it is the latter, stop the machine in time and remove the refrigerant.
The oil pump is severely worn and the gap is too large, resulting in the inability to build up oil pressure. In this case, repair the oil pump, and if the fault is serious, replace it directly.
Check whether the connecting rod bearing bush, main bearing bush, small end bushing of the connecting rod, and piston pin are severely worn. At this time, replace the relevant parts in time.
The gasket of the rear end cover of the crankcase is misaligned, blocking the oil inlet channel of the oil pump. Dismantle and check it, and refix the position of the gasket.
III. Maintenance Ideas for the Generation of a Large Amount of Foam in the Crankcase
The liquid hammer caused by the foaming of the lubricating oil in the crankcase is mainly caused by the following two reasons:
A large amount of refrigerant is mixed in the lubricating oil. When the pressure drops, the refrigerant will evaporate, severely generating a large amount of foam. In this case, evacuate the refrigerant in the crankcase.
Too much lubricating oil is added to the crankcase, and the large end of the connecting rod stirs the lubricating oil, causing a large amount of foam. In this case, drain some of the excessive lubricating oil in the crankcase so that the oil level reaches the specified oil level line.
IV. Maintenance Ideas for the Excessively High Oil Temperature
The assembly of the shaft and the bearing bush is not appropriate, and the gap is too small. Adjust the assembly gap between the shaft and the bearing bush to make the gap meet the standard requirements.
There are impurities in the lubricating oil, resulting in the scoring of the bearing bush. In this case, scrape the scored bearing bush flat and replace the oil with new oil. If the bearing bush is severely scored, replace it with a new one.
The shaft seal friction ring is installed too tightly or the friction ring is scored. Readjust the shaft seal friction ring. If the friction ring is severely scored, replace it with a new one.
If it is caused by the excessively high suction and discharge temperatures of the compressor, appropriately adjust the liquid supply valve of the system to make the suction and discharge temperatures return to normal.

V. Maintenance Ideas for the Increase in Pressure in the Crankcase
The piston ring is not tightly sealed, resulting in the leakage of high pressure to low pressure. Replace it with a new piston sealing ring.
The discharge valve plate does not close tightly, causing the pressure in the crankcase to rise. Check the sealing performance of the seat of the discharge valve plate. If it is not tightly sealed, replace the valve plate with a new one in time.
The sealing performance between the cylinder liner and the frame deteriorates. Remove the cylinder liner, clean the joint and seal it well, and then reassemble it.
Too much refrigerant enters the crankcase, and the pressure rises after evaporation. Just evacuate the excessive refrigerant in the crankcase.
VI. Maintenance Ideas for the Malfunction of the Energy Adjustment Mechanism
Check whether it is due to too low an oil pressure or a blocked oil pipe. If the oil pressure is too low, adjust and increase the oil pressure. If the oil pipe is blocked, clean and dredge the oil pipe.
Check whether the oil piston is stuck. Remove the oil piston, clean it, replace the dirty oil, and reassemble it correctly.
Check whether the installation of the pull rod and the rotating ring is incorrect, causing the rotating ring to be stuck. Focus on checking the assembly of the pull rod and the rotating ring, and repair it until the rotating ring can rotate flexibly.
Check whether it is caused by the improper assembly of the oil distribution valve. If so, use the air ventilation method to check whether each working position is appropriate, and readjust the oil distribution valve.
VII. Maintenance Ideas for the Excessively High Return Gas Superheat
Check whether the ammonia liquid in the evaporator is too little or the opening degree of the liquid supply valve is too small. If there is a lack of ammonia in the system, replenish it in time. If the liquid supply valve is improperly adjusted, open the liquid supply valve to an appropriate position.
Check whether the insulation layer of the return gas pipeline is poorly insulated or damaged due to moisture. Check the insulation layer comprehensively and replace it with new insulation materials.
The suction valve is leaking or has been broken. If the leakage is slight, grind the valve plate to stop the leakage. If it is broken, replace the suction valve plate with a new one directly.
VIII.
Maintenance Ideas for the Absence of Oil Pressure
Check whether there are any oil leakage or blockage at the connection points of the oil pump pipeline system. If there is oil leakage, tighten the joint. If there is a blockage, dredge the oil pipeline.
Check whether it is due to the oil pressure regulating valve being opened too much or the valve core falling off. If the oil pressure regulating valve is improperly adjusted, adjust the oil pressure regulating valve and adjust the oil pressure to the required value. If the valve core has fallen off, reinstall the valve core and fasten it firmly.
If there is too little oil in the crankcase or there is refrigerant, it will cause the oil pump not to draw in oil. If there is too little oil, add oil in time. If it is the latter, stop the machine in time and remove the ammonia liquid.
The oil pump is severely worn and the gap is too large, resulting in the inability to build up oil pressure. In this case, repair the oil pump, and if the fault is serious, replace it directly.
Check whether the connecting rod bearing bush, main bearing bush, small end bushing of the connecting rod, and piston pin are severely worn. At this time, replace the relevant parts in time.
The gasket of the rear end cover of the crankcase is misaligned, blocking the oil inlet channel of the oil pump. Dismantle and check it, and refix the position of the gasket.
IX. Maintenance Ideas for the Suction Pressure of the Compressor Being Lower than the Normal Evaporation Pressure
If the liquid supply valve is opened too small, it can lead to insufficient liquid supply, so the evaporation pressure will drop. In this case, just open the liquid supply valve to an appropriate degree.
The valve in the suction pipeline is not fully opened or the valve core has fallen off. If it is the former, open the valve fully. If the valve core has fallen off, reinstall the valve core.
There is a lack of refrigerant in the system. Even if the pressure valve is opened wide, the evaporation pressure is still low. At this time, replenish an appropriate amount of refrigerant according to the actual situation.
The return gas pipeline is thin, or there is a "liquid pocket" phenomenon in the return gas pipeline. If the pipe diameter is too thin, replace the return gas pipeline with a suitable one. If there is a "liquid pocket" phenomenon, remove the "liquid pocket" section in the return gas pipeline and weld the pipeline again.
X. Maintenance Ideas for the Wet Stroke of the Compressor
When the compressor starts, if the suction valve is opened too quickly, it will lead to a wet stroke.
Therefore, open the suction valve slowly when starting the machine to avoid a wet stroke and damage to the compressor.
If the opening degree of the liquid supply valve is too large, it will also lead to a wet stroke. At this time, just close the liquid supply valve appropriately.
When the cold storage returns to the normal temperature after defrosting, open the suction valve slowly and observe the operation of the refrigeration compressor at any time. If the return gas temperature drops too quickly, stop opening it temporarily, and continue to open it slowly after the operation returns to normal.
XI. Maintenance Ideas for the Knocking Sound in the Crankcase
Check whether the gap between the big end bearing bush of the connecting rod and the journal of the crankshaft is too large. At this time, adjust the gap or directly replace it with a new bearing bush.
If the gap between the main bearing and the main journal is too large, there will be collisions and friction, generating a knocking sound. Repair or replace it with a new bearing bush.
Check whether the cotter pin is broken and the connecting rod nut is loose. If so, replace the cotter pin with a new one and fasten the connecting rod nut.
If the center of the coupling is not correct or the keyway of the coupling is loose. Adjust the coupling, overhaul the keyway or replace the key with a new one.
The steel balls of the main bearing are worn and the bearing frame is broken. In this case, replace it with a new bearing.
XII. Maintenance Ideas for the Serious Oil Leakage of the Shaft Seal
Check whether the improper assembly of the shaft seal has caused serious oil leakage of the shaft seal. Assemble the shaft seal correctly.
Check whether the friction surface between the moving ring and the fixed ring is scored. If it is severely scored, carefully grind the sealing surface and reassemble it.
If the rubber sealing ring is aged or the tightness is not set properly, it will leak oil. In this case, replace the rubber ring with a new one and adjust the appropriate tightness.
Check whether the oil leakage of the shaft seal is caused by the weakening of the elastic force of the shaft seal spring. Remove the original spring and replace it with a new spring of the same size.
Check whether the sealing performance between the back of the fixed ring and the shaft seal gland has deteriorated. In this case, remove the fixed ring, clean the back ring and reassemble it.
If the pressure in the crankcase is too high, carry out adjustment operations. But before stopping the machine, first reduce the pressure in the crankcase and check whether the discharge valve is leaking.
XIII. Maintenance Ideas for the Overheating of the Cylinder Wall Temperature
If the oil pump malfunctions, resulting in too low an oil pressure or a blocked oil circuit, stop the machine for a comprehensive overhaul.
Check whether the gap between the piston and the cylinder wall is too small or the piston is offset. At this time, adjust the piston.
The safety block or the false cover is not tightly sealed, resulting in the leakage of high and low pressure. Take measures to repair it to improve the sealing performance.
Check whether the suction temperature is too high. Carry out adjustment operations to lower the suction temperature.
If the quality of the lubricating oil is poor and the viscosity is too small, stop the machine and replace the lubricating oil with new oil.
Check whether the scale in the cooling water jacket is too thick or the water volume is insufficient. If the scale is too thick, remove it in time. If the water volume is insufficient, increase the cooling water volume.
Check whether the suction and discharge valve plates are damaged. If they are damaged, replace the suction and discharge valve plates in time.
Check whether the piston ring is severely worn. If so, replace it with a new piston.