The working principle of the four-circuit protection valve is to divide the entire vehicle air circuit system into four interconnected and independent circuits to ensure that when any circuit fails, the other circuits can still maintain normal operation and inflation. The four-circuit protection valve is essentially a five-way joint that allows compressed air to enter the four-circuit protection valve through a specific inlet, and then be distributed to the four circuits of the system through the bypass hole and the one-way valve. When the preset opening pressure (protection pressure) is reached, the valve opens, the diaphragm bulges against the spring force, and the compressed air enters different circuits through the corresponding outlets.
The structure and function of the four-circuit protection valve include pressure regulation and diversion. It can flow compressed air into the gas tanks of circuits 1 and 2 of the service brake system, as well as circuits 3 and 4 through different outlets. Among them, circuit 3 is responsible for the air supply of the emergency brake and parking brake systems, and provides air source for the trailer, and circuit 4 is for the auxiliary brake system. When a circuit fails, other normally working circuits will provide air pressure supplement to the faulty circuit until the dynamic closing pressure point is reached. At this time, the spring force will close the valve to ensure that the remaining circuits are maintained above the safe pressure level.
The application scenario of the four-circuit protection valve is mainly in the commercial vehicle braking system to ensure that each circuit works independently and normally. Common faults include air blockage or air leakage in the pipeline. At this time, it is necessary to check whether the four-circuit protection valve and the one-way valve are stuck, or whether the diaphragm is broken. The design of the four-circuit protection valve enables it to quickly re-inflate from 0 bar when a circuit breaks or leaks, thereby protecting the normal operation of other circuits.
