What is a car valve spring
The valve spring of a car is a key component of the engine, located between the cylinder head and the spring seat at the tail end of the valve stem. Its main function is to ensure that the valve fits tightly against the valve seat when it is closed, preventing vibration from causing jumping and damaging the sealing performance.
Structure and Materials
It is usually made of high-quality alloy steel wire (such as medium carbon chromium-vanadium steel wire or silicon-chromium steel wire), and undergoes heat treatment to enhance fatigue strength. The surface is galvanized or phosphated to prevent rust. The two end faces of the spring need to be ground flat and perpendicular to the axis to avoid skewing during operation.
Function and Importance
Youdaoplaceholder0 Overcome inertial force : Counteract the inertial force of the transmission components during the valve closing process to prevent the formation of gaps among the components due to inertia.
Youdaoplaceholder0 Anti-vibration and runout : Prevent the valves from jumping when the engine vibrates to ensure sealing and avoid air leakage or valves falling into the cylinder and causing damage.
Youdaoplaceholder0 Design optimization : It mostly adopts a double-spring structure (with opposite inner and outer rotation directions), which enhances the anti-resonance ability and shortens the length. Even when a single spring breaks, it can still maintain some functions.
The functions of automotive valve springs mainly include the following three aspects:
Make sure the valves close in time and fit tightly
The valve spring ensures that the valve closely adheres to the valve seat or valve seat ring when closed through its own tension, preventing the valve from jumping and damaging the sealing performance due to engine vibration.
Overcome inertial force
When the valve is open, the spring needs to overcome the inertial force of the valve train to ensure that the transmission components are always controlled by the CAM. When the valves are closed, it is necessary to overcome the inertial force of the valves and transmission components to avoid the formation of clearance due to inertia.
Prevent resonance
It adopts variable pitch or double spring design (like a double spring in the center) to reduce the risk of resonance between the working frequency and the natural frequency, and prevent spring breakage. The double-spring structure can also maintain some functions when a single one breaks, enhancing reliability.
The fracture of the valve spring can cause abnormal operation of the engine, which is specifically manifested as:
Difficulty in starting
A broken valve spring can cause the valves to fail to open or close normally, directly affecting the engine's starting.
Unstable power
Abnormal operation of valves can lead to a decrease in intake and exhaust efficiency, causing problems such as unstable power output and increased fuel consumption.
The noise increases
Abnormal valve knocking can produce additional noise, and in severe cases, it may be accompanied by the sound of metal friction.
Shaking and abnormal noise
Periodic shaking may occur during engine operation, and abnormal noises may accompany the turning of the steering wheel in some models.
Maintenance suggestions
It is recommended to carry out immediate maintenance, replace the damaged spring and inspect the relevant components (such as valve guides, camshaft bearings, etc.). If not dealt with in time, it may cause the engine to overheat or suffer more serious damage.
The valve spring is located between the cylinder head and the spring seat at the tail end of the valve stem. The function of the valve spring is to ensure that the valve can be closely attached to the valve seat or valve seat ring when the valve is closed, and to overcome the inertial force generated by the valve train when the valve is open, so that the transmission components are always controlled by the CAM and do not separate from each other.
Valve springs are mostly made of high-quality alloy steel wire and undergo heat treatment to enhance their fatigue strength. To prevent the spring from rusting, the surface of the spring should be galvanized and phosphated. The two end faces of the spring must be ground flat and perpendicular to the spring's axis to prevent the spring from tilting during operation.
Valve springs are mostly cylindrical helical springs, as shown in Figure 1. When the working frequency of the valve spring is equal to or an integer multiple of its natural frequency, the valve spring will resonate, increasing the probability of breakage. To prevent resonance from occurring, variable-pitch springs can be adopted. Currently, most engines use double springs installed concentrically. The rotation directions of the inner and outer springs are opposite, and the stiffness of the outer spring is greater than that of the inner spring. Double springs not only prevent resonance but also shorten the length of the springs. And when one of the springs breaks, the other spring can still continue to work, preventing the valve from falling into the cylinder.
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