variable coil pitch spring 变螺距弹簧

electrically variable coil 电可变线圈

variable choking coil 可变扼流圈

variable induction coil 可变感应线圈

one-coil variable-inductance transducer 单线圈可变电感换能器

two-coil variable-inductance transducer 双线圈可变电感换能器

Variable Air Volume Fan-Coil Unit 可变风量室内送风机

variable stiffness coil spring 变刚度圆柱螺旋弹簧