Automotive engine valve
The role of the automotive engine valve is specifically responsible for inputting air into the engine and exhausting the burned exhaust gas. From the engine structure, it is divided into an intake valve and an exhaust valve. The role of the intake valve is to suck air into the engine and mix it with the fuel; the role of the exhaust valve is to exhaust the burned exhaust gas and dissipate heat.
The valve is composed of a valve head and a shank. Valve head temperature is very high (intake valve 570 ~ 670K, exhaust valve 1050 ~ 1200K), but also to withstand the pressure of gas, valve spring force and inertia force of the drive assembly, the lubrication and cooling conditions are poor, require the valve must has a certain strength, stiffness, heat resistance and wear resistance. The intake valve is generally made of alloy steel (chrome steel, nickel-chromium steel), exhaust valve with heat-resistant alloy (silicon-chromium steel). In order to save heat-resistant alloys, the head of the exhaust valve is made of a heat-resistant alloy, and the shank is made of chrome steel, and then the two are welded together.
Valve heads have flat tops, spherical tops, and horn tops. Flat top is generally used. The flat-top valve head has a simple structure, is easy to manufacture, has a small heat-absorbing area, a small mass, and can be used for both intake and exhaust valves. Spherical top valves are suitable for exhaust valves. They have high strength, low exhaust resistance, and good exhaust gas elimination effect. However, they have a large heated area, large mass and inertia, and complicated processing. The horn type has a certain streamlined shape, which can reduce the intake resistance, but its head has a large heating area and is only suitable for intake valves.
The valve material is usually divided into 40Cr, 4Cr9Si2, 4Cr10Si2Mo, 21-4N and 23-8N in China. 5Cr8Si2, 4Cr9Si3, 21-2N, 21-12N, 23-8N, XB, etc. have been used in large quantities on some imported models. High-temperature nickel-based alloys have also begun to be used on high-load diesel exhaust valves.
SIMUWU provide professional vacuum heat treatment furnace for automotive engine valve heat treating.
Tag: exhaust valve heat treatment, intake valve heat treatment, automotive engine valve heat treating
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