How does the material of the valve equipment affect the performance of the product?

Valve equipment plays a crucial role in the engine, responsible for controlling the intake and exhaust switching, directly affecting the performance, efficiency and life of the engine. The material selection of valve equipment has a profound impact on its performance, mainly reflected in the following aspects: heat resistance, wear resistance, corrosion resistance, mechanical strength, weight and manufacturing costs. The following will discuss in detail the effect of material on the performance of valve equipment.

1. Heat resistance

The valves are exposed to high temperatures during engine operation, especially the exhaust valves, which can operate at temperatures ranging from 700°C to 900°C. Therefore, the valve material must have good heat resistance to ensure that it can maintain stable mechanical properties and dimensional accuracy at high temperatures. If the heat resistance of the material is insufficient, the valve may be deformed, softened or even melted at high temperatures, resulting in the failure of the valve seal, which affects the compression ratio and combustion efficiency of the engine.

Commonly used heat-resistant materials include heat-resistant alloy steel, stainless steel and nickel-based alloys. For example, 21-4N (21% chromium, 4% nickel) is a commonly used exhaust valve material with excellent high temperature resistance. In addition, titanium alloys are gradually used in the valve manufacturing of high-performance engines because of their light weight and high heat resistance.

2. Wear resistance

The valve will frequently contact the valve seat during the working process, especially in the high-speed engine, the friction between the valve and the seat will lead to wear. If the wear resistance of the valve material is insufficient, the contact surface between the valve and the valve seat ring will gradually wear out, resulting in a loose valve seal, which will affect the compression ratio and combustion efficiency of the engine.

To improve wear resistance, valve materials usually require surface treatment, such as nitriding, carburizing or coating. For example, some valves are coated with a hard alloy, such as tungsten carbide or titanium nitride, to improve their wear resistance. In addition, the hardness of the valve material is also an important indicator, and materials with higher hardness usually have better wear resistance.

3. Corrosion resistance

During the operation of the engine, a large number of combustion products will be produced, such as sulfide, nitrogen oxides, etc., which will corrode the valve surface. Exhaust valves, in particular, are more susceptible to corrosion due to long-term exposure to high temperatures and corrosive gases. If the valve material corrosion resistance is insufficient, the valve surface will gradually be corroded, resulting in valve seal failure, which will affect the performance and life of the engine.

In order to improve corrosion resistance, valve materials usually need to add some corrosion resistant elements, such as chromium, nickel and so on. For example, stainless steel (such as martensitic stainless steel and austenitic stainless steel) is often used in the manufacture of valves because of its good corrosion resistance. In addition, some valve materials are also surface treated, such as chrome plating or corrosion resistant coating, to further improve their corrosion resistance.

4. Mechanical strength

The valve needs to withstand the repeated impact from the valve spring and the high-pressure gas action from the combustion chamber during the working process, so the valve material must have sufficient mechanical strength to resist these external forces. If the mechanical strength of the valve material is insufficient, the valve may break or deform during long-term operation, resulting in engine failure.

In order to improve mechanical strength, valve materials usually need to be heat treated, such as quenching and tempering, to improve their hardness and toughness. In addition, the composition design of the valve material is also very important, such as adding an appropriate amount of carbon, manganese, silicon and other elements, which can improve the strength and hardness of the material.

Step 5: Weight

The weight of the valve also has an important effect on the performance of the engine. The lighter valve can reduce the inertia force of the engine and improve the speed response and fuel economy of the engine. In addition, the lighter valve can also reduce the load of the valve spring and extend the life of the valve spring.

In order to reduce the weight of the valve, lightweight materials such as titanium alloy are often used. Titanium alloys not only have a high strength, but also a low density, is the ideal material for the manufacture of lightweight valves. However, titanium alloys have a higher cost and are usually only used in high-performance engines or racing engines.

6. Manufacturing cost

The cost of the valve material is also an important factor affecting its selection. High-performance materials, such as titanium alloys and nickel-based alloys, although they have excellent performance, their cost is higher and they are usually only used in high-end or special-purpose engines. In contrast, ordinary alloy steel and stainless steel have a lower cost and are widely used in ordinary automotive engines.

In order to strike a balance between performance and cost, valve manufacturers usually choose the right material for the specific requirements of the engine. For example, for ordinary family cars, it is common to choose a lower cost but sufficient performance valve material, while for high-performance engines or racing engines, a higher cost but better performance material will be selected.

7. Thermal conductivity

The valve needs to conduct heat rapidly to the valve seat and cylinder head during operation to prevent the valve from overheating. If the thermal conductivity of the valve material is poor, the valve may be deformed or damaged due to overheating, affecting the performance and life of the engine.

In order to improve thermal conductivity, the valve material usually needs to have good thermal conductivity. For example, aluminum alloy is often used to make valve seat rings because of its good thermal conductivity, and the valve material is usually selected as alloy steel or stainless steel with good thermal conductivity.

8. Coefficient of thermal expansion

The valve will experience drastic changes in temperature during operation, so the coefficient of thermal expansion of the valve material must match the material of the valve seat ring and cylinder head. If the coefficient of thermal expansion does not match, the valve may be stuck or sealed loosely at high temperatures, affecting the performance of the engine.

In order to ensure that the valve matches the coefficient of thermal expansion of the valve seat and cylinder head, the selection of the valve material usually needs to consider the overall design of the engine. For example, some engines use materials with a similar coefficient of thermal expansion to make valves and valve seats to ensure that they maintain good sealing performance at high temperatures.

conclusion

The material of the valve equipment has an important impact on its performance, heat resistance, wear resistance, corrosion resistance, mechanical strength, weight, manufacturing cost, thermal conductivity and thermal expansion coefficient and other factors need to be considered in the material selection. Different engine application scenarios have different requirements for valve materials, so valve manufacturers need to choose the right material according to their specific needs to ensure that the valve equipment can perform in the engine. With the development of materials science, there may be more high-performance, low-cost valve materials in the future, further promoting the progress of engine technology.