1. Cylinder stuck phenomenon
Cylinder stuck definition: It refers to the phenomenon that the relative moving parts of the compressor are unable to operate due to poor lubrication, impurities and other reasons. Compressor stuck cylinder indicates that the compressor has been damaged. Compressor stuck cylinder mostly occurs on the relative sliding friction bearing and crankshaft friction surface, the cylinder and the lower bearing, and the relative rolling friction piston and cylinder friction surface.
Misjudgment as a cylinder stuck phenomenon (compressor start failure): It means that the starting torque of the compressor cannot overcome the system resistance and the compressor cannot start normally. When the external conditions change, the compressor may start, and the compressor is not damaged.
Conditions for normal start-up of the compressor: Compressor starting torque > frictional resistance + high and low pressure force + rotational inertial force Frictional resistance: It is related to the friction between the compressor’s upper bearing, lower bearing, cylinder, crankshaft and the viscosity of the compressor’s refrigeration oil.
High and low pressure force: related to the balance of high and low pressure in the system.
Rotational inertia force: related to rotor and cylinder design.
2. Common causes of cylinder sticking
1. The reason of the compressor itself
The compressor is poorly processed, and the local force on the mating surface is uneven, or the processing technology is unreasonable, and impurities enter the interior of the compressor during the production of the compressor. This situation rarely occurs for brand compressors.
Compressor and system adaptability: Heat pump water heaters are developed on the basis of air conditioners, so most heat pump manufacturers continue to use air conditioner compressors. The national standard for air conditioners requires a maximum temperature of 43°C, that is, the maximum temperature on the condensing side is 43°C. ℃, that is, the temperature on the condensing side is 55 ℃. At this temperature, the maximum exhaust pressure is generally 25kg/cm2. If the ambient temperature on the evaporating side is 43℃, the exhaust pressure is generally about 27kg/cm2. This makes the compressor often in a high-load working state.
Working under high load conditions can easily cause carbonization of the refrigeration oil, resulting in insufficient lubrication of the compressor and cylinder sticking. In the past two years, a special compressor for heat pumps has been developed. Through the optimization and adjustment of internal structures such as internal oil return holes and exhaust holes, the working conditions of the compressor and heat pump are more suitable.
2. Causes of collisions such as transportation and handling
The compressor is a precision instrument, and the pump body is precisely matched. The collision and severe vibration during the handling and transportation will cause the size of the compressor pump body to change. When the compressor is started or running, the crankshaft drives the piston to a certain position. The resistance increases obviously, and finally gets stuck. Therefore, the compressor should be handled with care from the factory to the assembly into the host, from the storage of the host to the transportation to the agent, and from the agent to the user’s installation, so as to avoid the compressor being damaged. Collision, rollover, recumbent, etc., according to the relevant regulations of the compressor manufacturer, the handling tilt cannot exceed 30°.
3. Reasons for installation and use
For the air conditioner and heat pump industry, there is a saying of three points for quality and seven points for installation. Although it is exaggerated, it is enough to show that the installation has a great impact on the use of the host. Leaks, etc. will affect the use of the host. Let’s explain them one by one.
Level test: The compressor manufacturer stipulates that the running inclination of the compressor should be less than 5, and the main unit should be installed horizontally, and the inclination should be less than 5. Long-term operation with an obvious inclination will cause uneven local force and large local friction. detection.
Evacuation: Excessive emptying time will cause insufficient refrigerant, the compressor will not have enough refrigerant to cool, the exhaust temperature will be high, the refrigeration oil will be carbonized and deteriorated, and the compressor will be stuck due to insufficient lubrication. If there is air in the system, air is a non-condensable gas, which will cause high pressure or abnormal fluctuations, and the life of the compressor will be affected. Therefore, when emptying, it must be accurately emptied according to the standard requirements.
Post time: Feb-11-2023