Know A Little More About Your Engine’s Cylinder Valves

The modern internal combustion engine we are so used to today would never had become a practical invention without its means of controlling the intake and exhaust the air-fuel mixture: the cylinder valves. Most of us take these little parts for granted, but without these, the piston-based engines powering our cars would not operate efficiently. There is just no other practical means of opening and closing the combustion chamber of a gasoline engine.

The operation of valves are simple. On most engine designs, there is a camshaft that controls the timing of opening and closing of the cylinder valves. This is usually connected to the crankshaft by a series of gears or by a belt. The cams have lobes which push their corresponding valves. When the cam’s lobe pushes on the valve, it creates an opening inside the combustion chamber of engine. This allows the air or fuel mixture or exhaust gases to move in or out of the cylinder. When the cam rotates more, the valve is restored to its original position by a spring, effectively sealing the combustion chamber.

The valves in a four stroke engine have their respective positions at every stroke. With other gasoline engines, there have been some variation in valve positions per stroke, but they still operate on the same principles.

The intake stroke, as its name implies, is where the engine takes in its fuel and air mixture into the combustion chamber with the cylinder valves closed. The cams operate it on the intake port of the cylinder. The piston on this stage moves downwards, bringing the mixture into the cylinder.

Once the fuel mix is in, the cylinder valves usually close the intake as the piston moves up. This is now the compression stroke, where the piston compresses the air-fuel mixture into greater that atmospheric levels. The valves need to close on this stroke, if the mixture leaks out, the engine would not produce power at all.

Once the piston is near the top, the spark plug makes the mixture explode, sending the piston back down the cylinder. This action produces the power in the engine. They are kept closed here since the engine needs all the force of the explosion to move the piston downward. When the power stroke is done, the exhaust gases need to be expelled. The camshaft is usually tuned to open the exhaust valves so that the waste gases are pushed out on this stroke. The piston now moves up to aid in the exhaust of the gases, and then the strokes cycle back to the intake stroke.

Some engines may have variable valve timing in which the valves have different rates of operation with different engine speeds. But the cylinder valves simple principles of operation remain unchanged. They are still used to open or close the cylinders. If even one of these valves fail in an engine, this could render the whole engine totaled. Surely, the modern internal combustion engine is nothing without the valves that control it.

The job of the cylinder valves seems simple enough, but without these simple devices, the modern reciprocating-piston internal combustion engine could not have been commonplace. The gasoline engines we know today might not have even existed without these humble little parts.

Want to find out more about cylinder valves, then visit our site on how to choose the best ones for your needs.