Valves on Engine Introduction

Valves are one of the most import parts on engine. The valves are used to import air into engine and discharge exhaust gas having been burned.

In terms of engine structure, valves are classified into inlet valve and exhaust valve. Inlet valve is used to absorb air into engine, mixing with fuel and burning. Exhaust valve is used to discharge exhaust gas after being burned and cool. 

 

In China, the materials used for valves are classified into 40Cr, 4Cr9Si2, 4Cr10Si2Mo, 21-4N and 23-8N. 5Cr8Si2, 4Cr9Si3, 21-2N, 21-12N, 23-8N and XB have widely been used for engine on imported large machineries. High temperature nickel alloy is also used for exhaust valve on high load engine.  

 

On product structure, valves are generally classified into integer valve, double-metal butt welding valve and hollow sodium fill valve. Additional processes include top welding, top bead welding, conical surface bead welding, surface nitriding treatment, surface chromizing, etc.

 

The valves are used to import air into engine and discharge exhaust gas. On traditional engine, every cylinder has only an inlet valve and an exhaust valve. The structure is quite simple and has low cost, convenient for maintenance. The engine also has good low-speed performance. However, it is hard to improve power, especially on high ration speed, volumetric efficiency is low and performance is poor. To improve efficiency, multi-valve is adopted. Every cylinder has four valves in common (some cylinders have three or five valves, such as engine on Audi A6). Four cylinders have 16 valves in total. Sometimes, “16V” seen on automobile information means that the engine has 16 valves. The structure can compact chamber easily and fuel injector is located at the center. So fuel air mixture can be burned more quickly and equably. The weight and aperture of valves can be declined suitably so that valves can be opened or closed more rapidly.