[Mobile Equipment Technology Edition] Daily Question 20180408 Screw Refrigeration Compressor Gas Transmission Volume Adjustment Mechanism (8)

1. The screw unit cannot be unloaded: 　　The energy adjustment solenoid valve is damaged or does not work properly. There is a problem with the solenoid valve control system. For the refrigeration screw chiller with extreme energy adjustment in the SRC-S system, the sealing gasket under the flange cover is installed incorrectly. The sealing plate of the cylinder piston is damaged. The connecting rod of the piston cylinder is broken. The motor insulation is damaged. There is moisture in the motor winding. The motor of the screw chiller cannot be started. The cooling capacity required protection device is working. The compressor is at full load during the startup stage. The exhaust pressure is too small. The voltage value 2. The compressor of the screw unit cannot be loaded.: 　　The operating conditions of the screw unit are not within the specified application range, the oil temperature is too low but the density is too high, the capillary tube, oil filter, oil circuit, etc. are damaged, the energy adjustment solenoid valve is damaged or does not work properly, the solenoid valve damages the control system, the energy adjustment solenoid valve base sealing shaft gasket is damaged or is used or installed incorrectly, the energy adjustment valve, the cylinder piston is damaged, etc., etc., all will cause damage to the screw chiller or abnormal startup.

1. The compressor is in manual mode and cannot automatically increase or decrease load. 2. The piston is stuck, making it impossible to increase or decrease load. 3. The oil pressure is low or the oil circuit is clogged, and the piston cannot be pushed (I don’t know if this is correct...)

Compressor non-loading failure analysis and solutions The screw compressor unit non-loading failure is a common fault. The problem mainly occurs in the air conditioning system and related components. Systematic analysis of the screw compressor non-loading failure and proposing effective solutions is a reasonable way to solve the problem. 1. The air intake regulator is faulty or the loading pressure is set too low. The air intake regulator of CompAir air compressor consists of two parts: the power cylinder and the butterfly valve. Its working principle is: The system pressure overcomes the resistance of the pressure switch spring and controls the opening and closing state of the intake butterfly valve to realize unit loading and unloading. When the compressor starts, the air intake regulator is in a closed state, allowing the compressor to start under low load, reducing the load on the motor when starting, and facilitating the normal operation of the motor. After the compressor starts, the air inlet regulator opens and the compressor is loaded. If the piston, spring, and cylinder block in the power cylinder are misaligned or stuck with foreign objects due to improper use and maintenance, the air inlet butterfly valve cannot be opened, the air inlet is sealed, and the unit cannot load normally. The foreign objects need to be removed or damaged parts must be replaced. If there is a problem with the setting of the loading pressure, just set the loading pressure correctly. 2. Faulty loading/unloading solenoid valve or exhaust solenoid valve. The solenoid valve mainly plays an on-off function in the unit. The on-off state of the gas path is controlled by the solenoid valve's power on and off to realize the loading/unloading function. Usually, the loading/unloading solenoid valve is normally closed, and the purging solenoid valve is normally open. When the unit starts, the loading/unloading valve opens, and the compressed air drives the power cylinder butterfly valve to control whether air intake ； The purge solenoid valve is normally closed and the unit is loaded normally. If the loading/unloading valve fails, the unit will not be able to take in air normally. ； If the bleed valve fails, the unit is always in a bleed state. Both of the above situations will cause the unit to fail to load. The structure of the solenoid valve itself is not complicated, and the main reasons for its failure are:: 1. If the solenoid valve control coil is damaged, just replace the coil. 2. The diaphragm accessories in the solenoid valve have aged due to long-term use and cannot return to their original positions. The diaphragm accessories need to be replaced. 3. The gas channel hole in the solenoid valve is extremely small and may be blocked by impurities. The gas channel needs to be cleaned. 3. Pressure sensor failure The pressure sensor is used to detect unit pressure. If a malfunction occurs, the pressure display will be inaccurate. If the pressure sensor is used for loading detection, the unit cannot load normally. This type of fault can be solved by replacing the pressure sensor. 4. The air filter element is severely clogged. The air filter element is an important protective barrier for the compressor, and it is also the main component of the compressor air inlet. Once a serious blockage occurs, the compressor cannot complete the suction process, and the air filter element generally needs to be replaced. If it has not been used for a long time, the air filter element can be removed, blow from the inside out with compressed air, and clean the air filter element box and its pipes. Generally, the air filter should not be backflushed more than five times within a replacement cycle. Compressor not unloading failure analysis and solution The energy adjustment solenoid valve is damaged or does not work properly. There is a problem with the solenoid valve control system. For the refrigeration screw chiller with extreme energy adjustment in the SRC-S system, the sealing gasket under the flange cover is installed incorrectly, the sealing plate of the oil cylinder piston is damaged, the connecting rod of the piston cylinder is broken, the motor insulation is damaged, there is moisture in the motor winding, the screw chiller motor cannot start, the cooling capacity required protection device has worked, and the compressor is at full load during the startup stage. The exhaust pressure is too low and the voltage value is too low.

1. The screw unit cannot be unloaded: 　　The energy adjustment solenoid valve is damaged or does not work properly. There is a problem with the solenoid valve control system. For the refrigeration screw chiller with extreme energy adjustment in the SRC-S system, the sealing gasket under the flange cover is installed incorrectly. The sealing plate of the cylinder piston is damaged. The connecting rod of the piston cylinder is broken. The motor insulation is damaged. There is moisture in the motor winding. The motor of the screw chiller cannot be started. The cooling capacity required protection device is working. The compressor is at full load during the startup stage. The exhaust pressure is too small. The voltage value 2. The compressor of the screw unit cannot be loaded.: 　　The operating conditions of the screw unit are not within the specified application range, the oil temperature is too low but the density is too high, the capillary tube, oil filter, oil circuit, etc. are damaged, the energy adjustment solenoid valve is damaged or does not work properly, the solenoid valve damages the control system, the energy adjustment solenoid valve base sealing shaft gasket is damaged or is used or installed incorrectly, the energy adjustment valve, the cylinder piston is damaged, etc., etc., all will cause damage to the screw chiller or abnormal startup.

Solenoid valve failure, intake valve failure, pressure detection failure

1. The screw unit cannot be unloaded: 　　The energy adjustment solenoid valve is damaged or does not work properly. There is a problem with the solenoid valve control system. For the refrigeration screw chiller with extreme energy adjustment in the SRC-S system, the sealing gasket under the flange cover is installed incorrectly. The sealing plate of the cylinder piston is damaged. The connecting rod of the piston cylinder is broken. The motor insulation is damaged. There is moisture in the motor winding. The motor of the screw chiller cannot be started. The cooling capacity required protection device is working. The compressor is at full load during the startup stage. The exhaust pressure is too small. The voltage value 2. The compressor of the screw unit cannot be loaded.: 　　The operating conditions of the screw unit are not within the specified application range, the oil temperature is too low but the density is too high, the capillary tube, oil filter, oil circuit, etc. are damaged, the energy adjustment solenoid valve is damaged or does not work properly, the solenoid valve damages the control system, the energy adjustment solenoid valve base sealing shaft gasket is damaged or is used or installed incorrectly, the energy adjustment valve, the cylinder piston is damaged, etc., etc., all will cause damage to the screw chiller or abnormal startup.

1. The screw unit cannot be unloaded: 　　The energy adjustment solenoid valve is damaged or does not work properly. There is a problem with the solenoid valve control system. For the refrigeration screw chiller with extreme energy adjustment in the SRC-S system, the sealing gasket under the flange cover is installed incorrectly. The sealing plate of the cylinder piston is damaged. The connecting rod of the piston cylinder is broken. The motor insulation is damaged. There is moisture in the motor winding. The motor of the screw chiller cannot be started. The cooling capacity required protection device is working. The compressor is at full load during the startup stage. The exhaust pressure is too small. The voltage value 2. The compressor of the screw unit cannot be loaded.: 　　The operating conditions of the screw unit are not within the specified application range, the oil temperature is too low but the density is too high, the capillary tube, oil filter, oil circuit, etc. are damaged, the energy adjustment solenoid valve is damaged or does not work properly, the solenoid valve damages the control system, the energy adjustment solenoid valve base sealing shaft gasket is damaged or is used or installed incorrectly, the energy adjustment valve, the cylinder piston is damaged, etc., etc., all will cause damage to the screw chiller or abnormal startup.

　The energy adjustment solenoid valve is damaged or does not work properly.

1. Analysis of the reasons why the screw air compressor cannot be unloaded: ①The pressure switch is improperly set or drifts after setting, reporting false numbers. ； ②Poor operation of the intake valve, jamming, etc. ； ③When the system stops using gas, the release solenoid valve fails, and the performance state is that the pressure slowly rises, instead of rising all at once like loading. ④Control loop failure ； ⑤The loading solenoid valve is faulty. The phenomenon is that it is unloading but loading at the same time. The loading air volume is greater than the unloading, so the pressure continues to increase. ； 2. Analysis of the reasons why the screw air compressor cannot be uploaded: 1. Check whether the unloading valve (intake valve) is stuck. If not, start the air compressor and loosen the air pipe screw from the regulator to the unloading valve. If the air pressure comes up, the regulating valve is faulty. 2. The fault has not been eliminated, and the air inlet channel is artificially opened (note that someone must open the exhaust valve, and can open all the exhaust valves at any time as needed. In this state, the load is out of control to ensure safety). In terms of air pressure, the regulating system fails, the air pressure does not increase, and the compressor fails. 3. For air pressure, disconnect the electric control device. If it is normal, the electronic control system is faulty (many air compressors now have electronic control systems, and several indicators of the engine control the regulator). 4. If it is not an electronic control failure, just find the cause on the regulator.