Have you ever wondered what those ordinary looking valves in a car engine actually do? You may just think of them as part of a component, but in fact, valves play a vital role in the proper operation of the engine. In this article, we will reveal the role of engine valves and answer this question for you. First, let's take a look at the basic structure of the valve. A valve is a switch in an engine that controls fluid flow in and out. It is usually located on the cylinder head and opens or closes the valve by moving it up and down. When the valve is opened, the gas mixture or air can enter the cylinder; When the valve is closed, the cylinder will be closed, and the combustion gas cannot escape. Next, we will focus on the three main roles of engine valves.