What is the working principle of an automotive exhaust gas valve?

[OAndrew]

An automotive exhaust gas valve, also known as an oil-gas/water-oil separator, operates on the principle that high-pressure gas from the compressor, including gaseous working medium and lubricating oil, enters the exhaust gas valve and flows into its guide vanes. The gas then moves in a spiral pattern along the guide vanes, where centrifugal force and gravity separate the lubricating oil from the working medium gas, causing the oil to flow down along the inner wall of the cylinder. The working medium gas is then drawn out of the exhaust gas valve through a central pipe via a multi-baffle system. Below are some relevant details: Separated lubricating oil: It accumulates at the bottom of the oil separator and can be periodically drained or automatically returned to the compressor's crankcase using a float valve. Function of the automotive exhaust gas valve: It allows exhaust gas to re-enter the cylinder for recirculation and combustion, which slightly reduces the combustion temperature in the cylinder and lowers the NOX content in the exhaust. When the throttle reaches a certain opening, the exhaust gas valve opens, directing exhaust gas from the cylinder to the intake pipe and then back into the cylinder for recirculation and combustion, thereby fully burning the exhaust gas and purifying the air.