双金属开关是一种控制工程组件，一旦达到定义的温度，它就会引起某种动作，例如关闭过程以避免过热。它基于这样一个事实，即在变化的热条件下，每种金属都会根据固定的热膨胀系数膨胀或收缩。因此，双金属，一种由两条不同金属(例如钢和锌)相连的条带制成的组件，会在温度变化时弯曲。一旦弯曲应变达到开关设计者定义的极限，双金属开关就会被激活。

　　A bimetallic switch is a control engineering component which causes a certain action once a defined temperature is reached, e.g. switching off a process in order to avoid overheating. It is based on the fact that under changing thermal conditions every metal expands or contracts according to a fixed thermal expansion coefficient. Hence the bimetal, a component made of two connected strips of different metals (e.g. steel and zinc), bends when the temperature changes. Once the bending strain reaches the limit defined by the designer of the switch, the bimetallic switch is activated.