The role of the four-way valve: To change the flow direction of the refrigerant gas in the heating system. To change the function of the evaporator and the condenser, so that the heat pump can be a heating device or cooling device freely.
And the other important function of our-way valve is : to remove the frost on evaporator by chaning the refrigerant flowing direction. During the low-temperature heating process of the heat pump, frosting will inevitably occur in the evaporator, and the thickness of the frost layer will gradually increase with time passing, gradually the frost will reduce the heating capacity of the heat pump.
Therefore, in order to maintain the heat exchange capacity and improve the heat exchange efficiency of the heat exchanger, it is necessary to switch the refrigerant through the four-way valve to make heat pump defrost.
The working principle is that when the solenoid valve coil is in the power-off state, as shown in the figure, the pilot spool valve is driven to the left by the right compression spring, and the high-pressure gas enters the capillary tube and enters the right-end piston chamber. On the other hand, the gas of the left-end piston chamber is discharged. Due to the pressure difference between the two ends of the piston, the piston and the main spool are moved to the left, so that the exhaust pipe is connected to the condenser unit, and the other two pipes are connected to each other to form a refrigeration cycle.