In the air-conditioning heat pump system, the four-way valve changes the refrigerant flow direction in winter and summer to switch the refrigeration and heating modes of the system.
our-way valve by the main valve and pilot valve, including the main valve on the 4 nozzle, the upper 1 lower 3, and pilot valve control of the 4 different connections between the nozzle.
One nozzle on the upper part of the main valve is connected with the exhaust of the compressor, and among the three nozzles on the lower part, the middle is connected with the suction of the compressor, and the remaining two nozzles on the left and right are connected with the heat exchange coil pipes of the indoor and outdoor machines respectively, that is, evaporators and condensers.
From the compressed refrigeration cycle flow to know, the compressor exhaust to the condenser, compressor suction from the evaporator. Therefore, the left and right two nozzles of the four-way valve are connected with the exhaust gas of the upper compressor, which leads to the condenser, while the other is connected with the return gas of the evaporator, which is communicated with the intermediate nozzles in the four-way valve, then to the suction end of the compressor.
Four-way valve mode switch is to change the compressor suction and exhaust and the direction of communication between the internal and external units, thereby changing the flow direction of refrigerant, so that indoor and external units are used as evaporators or condensers.
There is a slide valve in the guide valve of the four-way valve, which moves under the action of the spring force and the electromagnetic force (when electrified) in the valve, changes the passage in the guide valve, and controls the compressor exhaust to enter the left or right side of the piston in the main valve, thus changing the piston pressure difference between the left and right sides.
The piston in the main valve moves under the action of pressure difference, moving in place will cover 2 out of 3 nozzles, so that the remaining 1 nozzles connected with the upper nozzles, then the upper compressor exhaust is the condenser. The two covered nozzles are connected under the piston, and the side is connected with the evaporator return gas, which is sent to the suction end of the compressor through the middle nozzles.
In general, the four-way valve is used as the refrigeration mode when the power is off. At this time, the slide valve in the pilot valve is only affected by the spring force, and the slide valve movement changes the pressure difference between the two sides of the piston of the main valve, move the piston to the nozzle and middle nozzle that cover the interior side of the unit.
At this time, the indoor machine for the evaporator (endothermic evaporation to refrigeration) , the return gas into the four-way valve, from the intermediate interface to the compressor suction end. Outdoor unit for the condenser (exothermic condensation to exhaust heat) , from the four-way valve connected to the upper compressor exhaust, through the piston outside the tube to the outdoor unit.
When the four-way valve is electrified, it is in heating mode. The spool valve in the pilot valve moves to the other side under the action of electromagnetic force.
At this point, the outdoor unit for the evaporator (from the outdoor air absorption heat) , return into the four-way valve, from the middle interface to the compressor suction end. Indoor unit for the condenser (exothermic condensation to heating) , from the four-way valve connected to the upper compressor exhaust, through the piston outside the tube to the indoor unit.
