The other data of valve spring

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Some output parameters are constrained by design constraints. For example, installation length and average diameter of springs are restricted by packing space. The maximum spring compression and torsional stress at the compaction length are limited by the fatigue life, strength and maximum allowable stress limit of the spring. The constraint condition of spring flutter protection is achieved by controlling the physical clearance and the natural frequency of the spring. The order of spring flutter refers to the ratio of the natural frequency of the spring to the working frequency of the engine. In order to ensure that the spring is not running strong flutter. The natural frequencies of valve springs should normally be at least 13 times the engine operating frequencies, and the order of spring flutter is expected to be higher than 13. The natural frequency analysis of the spring shows that if the spring is very sensitive to one of the dominant harmonics of the cam profile, the flutter trend certainly exists. In this case, it is necessary to modify the design of cam or spring. Sometimes variable stiffness or nested springs can be used to change the frequency of the spring to help alleviate flutter.

Spring design is a juiceless problem of multi-dimensional parameters, which can be handled in a graphical way to check the trend of parameter sensitivity. The purpose of valve spring design optimization is to maximize the natural frequency of the spring to reduce spring vibration, while satisfying the following restrictions: (1) spring preload and valve spring stiffness required by engine system, (2) maximum allowable spring stress, (3) appropriate solid clearance to control spring flutter.