机动车发动机上的一些弹簧,总是处于高频往复运动或振动中,虽然它们很少折断损坏,但其弹力大小对发动机工作状况有较大影响。当发动机工作状况高速时就出现高速不稳,易熄火,功率下降等故障。不同机型的气门弹簧,其弹力、自由高度等都有严格要求,在长期使用后,因受高温退火作用,弹簧逐渐疲劳变软、弹力下降,气门 Some of the spring on the engine of motor vehicle are always in the high-frequency reciprocating motion or vibration. Although they are rarely broken and damaged, their spring force has a great influence on the working condition of the engine. When the engine working conditions at high speed instability, easy to turn off, power down and other failures. Different models of the valve spring, its elastic, free height and so have strict requirements, after long-term use, due to high temperature annealing, the spring gradually fatigue softening, elastic decline, the valve