The lift of the valve depends on

The lift of the valve depends on the shape of the cam profile.

Brief introduction of valve:

The function of the valve is specially responsible for inputting air into the engine and discharging exhaust gas after combustion. From the engine structure, it can be divided into intake valve and exhaust valve. The function of the intake valve is to draw air into the engine and mix it with fuel for combustion; The function of the exhaust valve is to exhaust the exhaust gas after combustion and dissipate heat.

Structure of valve:

The valve consists of a valve head and a stem. The valve head temperature is very high (intake valve 570~670K, exhaust valve 1050~ 1200K), and it also bears the pressure of gas, the force of valve spring and the inertia force of transmission assembly. Its lubrication and cooling conditions are poor, which requires the valve to have certain strength, stiffness, heat resistance and wear resistance.

Generally, the intake valve adopts alloy steel (chrome steel, nickel-chrome steel), and the exhaust valve adopts heat-resistant alloy (silicon-chrome steel). Sometimes in order to save heat-resistant alloy, the exhaust valve head is made of heat-resistant alloy and the valve stem is made of chromium steel, and then the two are welded.

Present situation and materials of valves;

1, current situation

In order to improve the efficiency of intake and exhaust, multi-valve technology is often used. It is common that each cylinder is equipped with four valves (there are also three or five valves in a single cylinder, and the principle is the same, such as the engine of Audi A6). There are * * valves 16 in the four cylinders, and the "16V" we often see in the automobile data is * * 65438+.

This multi-valve structure is easy to form a compact combustion chamber, and the fuel injector is arranged in the center, so that the fuel-air mixture burns faster and more evenly, and the weight and opening of each valve can be reduced appropriately, so that the valves can be opened or closed faster.

2. Materials

In China, the materials of valves are usually divided into 40Cr, 4Cr9Si2, 4Cr 10Si2Mo, 2 1-4N and 23-8N. 5Cr8Si2, 4Cr9Si31-2n, 2 1- 12N, 23-8N, XB, etc. It has been widely used in some imported models. High-temperature nickel-based alloys have also been used in exhaust valves of high-load diesel engines.