Analysis of the Main Functions and Components of Refrigeration Air Conditioners

Scroll Compressor:
The structure of the compressor is mainly composed of a moving scroll, a fixed scroll, a cross slide ring, a crankshaft, a bracket, a casing, etc. The scroll is installed at the upper part of the casing. The fixed scroll and the motor stator are installed on the inner wall of the casing. The cross slide ring is a circular ring with two pairs of mutually perpendicular convex keys set on the upper and lower surfaces. The upper convex keys are installed in the keyways on the back of the moving scroll, and the lower convex keys are installed in the keyways of the bracket.

The function of the cross slide ring is to prevent the moving scroll from tilting and rotating on its own. There is a back pressure chamber below the moving scroll. The back pressure chamber is automatically inflated with medium-pressure gas introduced through the small holes on the bottom plate of the moving scroll, so that the pressure in the air chamber supports the moving scroll.
Oil Separator:
In order to prevent a large amount of lubricating oil discharged from the compressor from entering the pipeline system, an oil-gas separator is installed between the condenser and the exhaust port of the compressor.

When the mixture of refrigerant and oil enters the oil separator, its speed decreases. Through the effects of gravitational sedimentation and centrifugal force, the refrigeration oil is separated from the refrigerant and deposited at the bottom. The refrigerant is discharged from the oil separator through the standpipe.
Gas-Liquid Separator:
The gas-liquid separator is a device that protects the compressor in the suction process of the refrigeration system. It separates the gas and liquid in the return gas to prevent the low-pressure and low-temperature wet vapor returning to the compressor from carrying too many liquid droplets, and to avoid the liquid refrigerant from entering the compressor and causing the liquid hammer fault.
Check Valve:
It is installed at the exhaust end of the compressor and on the bypass return circuit of the electronic expansion valve to prevent the refrigerant from flowing back.
Four-Way Valve:
The four-way valve is mainly composed of three parts: a pilot valve, a main valve, and an electromagnetic coil. The electromagnetic coil can be disassembled. The pilot valve and the main valve are welded into one body.
Working Principle of the Refrigeration Four-Way Valve:
In the refrigeration working condition, the four-way valve changes direction to connect the solid lines in the diagram. At this time, the indoor heat exchanger becomes an evaporator, and the outdoor heat exchanger becomes a condenser. The low-temperature and low-pressure superheated gas from the indoor heat exchanger enters the gas-liquid separator through the four-way valve and the muffler. After separating the liquid, the dry superheated gas is sucked in by the compressor, compressed into a high-temperature and high-pressure gas, and discharged. The gas enters the outdoor heat exchanger through the four-way valve, releases heat and condenses into a subcooled liquid. After the subcooled liquid is depressurized by the resistance of the capillary tube, it becomes a low-temperature and low-pressure two-phase fluid, enters the indoor heat exchanger to evaporate and absorb heat (at this time, the indoor air is cooled), and then enters the next cycle through the four-way valve and the gas-liquid separator. The filter is mainly used for separating the refrigerant from the compressor oil to ensure the heat exchange efficiency of the heat exchanger.
Working Principle of the Heating Four-Way Valve:
When the heat pump type air conditioner operates in the heating working condition, the indoor heat exchanger becomes a condenser, and the outdoor heat exchanger becomes an evaporator. The low-temperature and low-pressure superheated gas from the outdoor heat exchanger enters the gas-liquid separator through the four-way valve and the muffler. After separating the liquid, the dry superheated gas is sucked in by the compressor, compressed into a high-temperature and high-pressure gas, and discharged. The gas enters the indoor heat exchanger through the four-way valve, releases heat and condenses (at this time, the indoor air is heated), and becomes a subcooled liquid. After the subcooled liquid is depressurized by the resistance of the capillary tube, it becomes a low-temperature and low-pressure two-phase fluid, enters the outdoor heat exchanger to evaporate and absorb heat, and then the superheated gas enters the next cycle through the four-way valve and the gas-liquid separator.
Electronic Expansion Valve:
The electronic expansion valve is composed of a stepping motor coil and a valve body component with a magnetic rotor. The rotor component is enclosed in the outer cover of the valve body. When the pulse voltage is input to the stator coil of the electronic expansion valve according to a certain logical sequence, a rotating magnetic field is generated. The rotor made of a magnet rotates under the action of the magnetic torque, and through the transmission mechanism (thread), the valve needle moves up and down to change the opening size of the valve port. Thus, the flow channel area of the valve port is adjusted, the flow rate of the refrigerant is regulated, and the refrigeration system is kept in the best state. The one directly driven by the motor to move the valve plug is of the direct-acting type; the one driven by the motor through gear reduction to move the valve plug is of the reduction type.
Pressure Switch:
When the pressure of the controlled medium rises to a certain set value, the butterfly-shaped metal diaphragm becomes unstable and jumps. By pushing the push rod, the switch contacts are disconnected (or connected). When the pressure of the controlled medium drops to another set value, the butterfly-shaped metal diaphragm will suddenly jump back to its original state in the opposite direction, making the switch contacts connect (or disconnect), thus realizing the function of the switch and providing safety and control protection for the system.
Solenoid Valve:
When the coil is energized, an electromagnetic force is generated to suck up the movable iron core, and the medium in the main valve cavity leaks out from the pilot valve port, resulting in a pressure difference. The valve cup is quickly lifted up, and the main valve port is opened. When the coil is de-energized and the magnetic field disappears, the movable iron core returns to its original position, closes the pilot valve port, and the refrigerant enters the upper cavity from the balance hole.

After the pressure in the pilot valve and the main valve cavity is balanced, the valve returns to the normally closed position.
Stop Valve:
It is used to connect and cut off the refrigerant pipeline, and can also be used for operations such as detection, evacuation, and refrigerant addition.
Detection Connector:
It is mainly installed on the oil separator, the suction pipe, the exhaust pipe, and the high and low pressure sensor components. It is mainly used for pressure detection, refrigerant inspection, and the connection of the pressure sensor components.