About the valve

The role of the valve

The role of the valve is specifically responsible for the input of air into the engine and exhaust the exhaust gas after combustion. From the engine structure, it is divided into intake valve and exhaust valve. The role of the intake valve is to draw air into the engine and mix it with the fuel to burn; The function of the exhaust valve is to discharge the exhaust gas after combustion and dissipate heat.

The composition of the valve

The valve is composed of a valve head and a rod. The valve head temperature is very high (intake valve 570~670K, exhaust valve 1050~1200K), but also withstand the pressure of the gas, the valve spring force and the transmission component inertia force, its lubrication, cooling conditions are poor, requiring the valve must have a certain strength, stiffness, heat and wear resistance. The intake valve is generally made of alloy steel (chromium steel, nickel-chromium steel), and the exhaust valve is made of heat-resistant alloy (silicon chromium steel). Sometimes in order to save heat resistant alloy, the exhaust valve head is made of heat resistant alloy, and the rod is made of chromium steel, and then the two are welded together. The shape of the valve head has a flat top, a spherical top and a horn top. Usually a flat top is used. The flat-top valve head has the advantages of simple structure, convenient manufacture, small heat absorption area, small mass, and can be used for inlet and exhaust valves. The spherical top valve is suitable for the exhaust valve, which has high strength, small exhaust resistance and good exhaust gas elimination effect, but it has a large heating area, large mass and inertia, and complex processing. The horn type has a certain streamline, which can reduce the intake resistance, but its head is heated by a large area, which is only suitable for the intake valve. The valve cone Angle is the Angle of the valve sealing surface, which is generally 45° and some are 30° (CA1091 type 6102 engine). The valve of 30° is considered the same lift, the valve taper is small, the valve through the end face is large, and the intake resistance is small, but because the valve head edge of the small taper is thin, the stiffness is small, the sealing and thermal conductivity are poor, it is generally used for the intake valve. The thickness of the valve edge is generally 1~3mm to prevent damage or burning by high temperature due to impact with the valve seat in the work. In order to reduce the intake resistance and improve the intake efficiency of the cylinder, the intake valve of most engines is larger than the exhaust valve. The used intake and exhaust valves are also different colors. The valve rod is cylindrical, constantly reciprocating in the valve guide, and its surface must be superheated and polished. The shape of the end of the valve rod depends on the fixed form of the valve spring, the commonly used structure is two half lock pieces to fix the spring seat, the end of the valve rod has a ring groove to install the lock piece, some are fixed with the lock pin, and the end has a hole for installing the lock pin.

The shape of the valve

In order to improve the efficiency of intake and exhaust, more and more valve technology is now used, it is common that each cylinder arrangement has 4 valves (there are also 3 or 5 valves of a single cylinder design, the principle is the same, such as Audi A6 engine), 4 cylinders is a total of 16 valves, we often see on the car data "16V" means that the engine has 16 valves. This multi-valve structure is easy to form a compact combustion chamber, and the injector is arranged in the center, which can make the oil and gas mixture burn more quickly and more evenly, and the weight and opening of each valve are appropriately reduced, so that the valve is opened or closed faster.

Materials

The material of the valve in China is usually divided into 40Cr, 4Cr9Si2, 4Cr10Si2Mo, 21-4N and 23-8N. 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 been applied to the exhaust valves of high-load diesel engines.

Motorcycle valve

Valve products for motorcycle engine models, including intake and exhaust valves. Such as CG125, CG150 and other models of products.

General purpose engine valve

Valve products for general purpose gasoline models, including intake and exhaust valves.

Diesel valve

It is suitable for valve products in general diesel engines, including intake valve and exhaust valve. Such as GR140, S195/R185 and other models.