Unloading valve assembly for compressed air processing system in a commercial vehicle

An unloading valve assembly for compressed air processing system in a commercial vehicle, comprising:

• a valve body having an inner space extending in an axial direction, and including a first inlet through which a first control input of compressed air is introduced according to an operation of a first control valve, a second inlet through which a second control input of compressed air is introduced according to an operation of a second control valve, and a main outlet through which the compressed air of the inner space between the first inlet and the second inlet can be discharged to the outside;
• a piston including a piston head configured to receive the second control input by compressed air introduced from the second inlet and a pressurizing rod extending from the piston head in the axial direction and having an outer diameter smaller than that of the piston head, wherein the piston is inserted into the inner space of the valve body and configured to communicate with the second inlet to be axially movable by the second control input;
• a hollow adapter inserted and fixed into the inner space of the valve body, including a first opening communicating with the first inlet and a second opening through which a part of the piston can pass, and having a valve seat settling surface formed thereon;
• a valve seat installed inside the hollow adapter to open the second opening of the hollow adapter while being pressurized by the piston and guided in the axial direction, wherein the valve seat further includes a pressurizing rod settling surface capable of being in contact with the pressurizing rod of the piston, the valve seat forms an airtightness with the valve seat settling surface of the hollow adapter outside of the pressurizing rod settling surface;
• a cover fixed to the valve body;
• and
• a first spring member compressibly installed between the cover and the valve seat.