Engine valves are mechanical components used in internal combustion engines to allow or restrict the flow of fluid or gas to and from the combustion chambers or cylinders during engine operation. More information concerning other about other valve types may be found in our related guide Understanding Valves.

What are valve events?

The term “valve event” refers to the opening or closing of either the intake or the exhaust valve(s) with reference to piston TDC or BDC. The graph below shows the intake and exhaust valve events as they would typically appear around the end of the exhaust stroke (TDC).

What is an engine valve called?

The valve which allows mixture into the cylinder is the inlet valve; the one through which the spent gases escape is the exhaust valve. They are designed to open and close at precise moments, to allow the engine to run efficiently at all speeds. This is called an overhead-valve (OHV) system.

What is meant by valve lag?

The number of degrees of crankshaft rotation after a piston passes the top or bottom center of its stroke, at which the intake or exhaust valves open or close. …

What causes engine valve damage?

In the failure analysis of a valvetrain, valve failures represent the most common problems. The major causes of valve failure are distortion of the valve seat, deposits on the valve, small tappet clearance, burnt valve, erosion of valves, heat fatigue, pitting, breaks, and wear [1, 2].

What are the types of engine valves?

There are 3 different types of engine valves as follows: Poppet valve. Sleeve valve. Rotary valve….

• Poppet Valve. It is also known as mushroom valve because of its shape.
• Sleeve Valve.
• Rotary Valve.

What is the benefit of valve overlap?

Valve overlap is designed into the engine and is most useful at higher speeds. At higher speeds, the extra amount of intake charge brought into the combustion chamber provides a substantial increase in available power. The amount of time that both valves are open in directly related to engine rpm.

What is the most important valve event?

IVC is considered by many to be the most important timing event decision affecting both performance (peak torque) and/or economy. IVC is a major component of Volumetric Efficiency. The amount of the air/fuel charge is predominantly controlled by IVC.

What is the purpose of valve lag?

Intake valve lag helps to intake more air/fresh charge by the help of inertia effect of flowing air/ air-fuel mixture. Exhaust valve lead helps to increase overall efficiency by decreasing the work done required to forcing out the burned gas.

What is a valve timing diagram?

A valve timing diagram is a graphical representation of the opening and closing of the intake and exhaust valve of the engine, The opening and closing of the valves of the engine depend upon the movement of piston from TDC to BDC, This relation between piston and valves is controlled by setting a graphical …