Description
Core Functions and importance
The exhaust valve is one of the core components of the engine's valve train, and its core function is to precisely control the discharge of exhaust gases after combustion. It works in coordination with components such as intake valves, camshafts, and valve springs. The specific working process is as follows:
Closed state: During the compression and power strokes, the exhaust valve is tightly closed to ensure the combustion chamber is sealed and to maintain the combustion pressure.
In the open state: During the exhaust stroke, the exhaust valve opens on time driven by the camshaft, allowing the high-temperature and high-pressure exhaust gas to be discharged from the cylinder into the exhaust manifold, and then discharged into the atmosphere through the three-way catalytic converter and muffler.
The working environment of exhaust valves is extremely harsh. They need to withstand high temperatures of exhaust gases ranging from 800°C to 900°C and continuous impact wear. Therefore, the requirements for their materials and manufacturing processes are very high.
2. Technical features and Materials
Material: 13715-50060 Exhaust valves are typically made of high-heat-resistant alloy steel, with the most common material being 21-4N (an austenitic steel). This material can maintain extremely high strength and hardness at high temperatures, and has excellent oxidation resistance and corrosion resistance, making it highly suitable for the working requirements of exhaust valves.
Structural design
Hollow sodium-filled technology: Some high-performance versions of this model's exhaust valve may adopt a hollow sodium-filled design. The inside of the valve stem is hollow and about half of metallic sodium is injected. Sodium melts at approximately 97° C. As the valves move up and down, the liquid sodium shakes vigorously in the cavity, which can conduct heat extremely efficiently from the hottest valve head to the cooler valve stem, and then transfer it to the engine cooling system through the valve guide. This is a very important heat dissipation technology that can significantly reduce the temperature of the valve head (by approximately 100°C), preventing the valves from overheating and burning.
Conical surface surfacing: To enhance wear resistance, the sealing conical surface where the valve contacts the valve seat ring is usually surfacing with wear-resistant alloys (such as Stellite alloy) to extend its service life.
3. Main application vehicle models/engines
This exhaust valve is mainly used for Toyota's 2AZ-FE engine and models that use this engine or similar structures.
Common vehicle models include:
Toyota Camry (especially the sixth-generation models around 2006 to 2011)
Toyota RAV4 (third-generation model)
Toyota Yizhi
Scion tC
Some Lexus models (such as ES, etc., but the specific engine model needs to be confirmed)
