曲线能精确表明热动元件在温度范围内工作时推杆的升程变化。曲线分两部分：升温曲线-温度上升时感温蜡膨胀；降温曲线-温度降感温蜡体积缩小。这两个曲线同升程时的温度差值为滞后性。这是内部零件压缩和摩擦以及热惯性引起的。曲线的形状和斜率取决于感温蜡的膨胀率。
The curve below demonstrates what you would see if you graphed the performance of one of our thermal actuators. Our expansion curves graphically display an actuator’s performance as it heats up and cools down. Hysteresis is defined as the differential between the graphed upstroke and down stroke, this differential is caused by the thermal inertia within the actuator.
