一、进口单作用气动执行器概述

单作用气动执行器在通气的情况下气动执行器打开阀道门，不通气源的情况下自动关闭，单作用气动执行器靠弹簧自动复位，一般在危险的工况中使用较多，比图输送可燃气体或可燃液体，在失去气源又出现紧急情况的时候，单作用气动执行机内构能自动复位把危险降到最低，而双作用一般不容易复位。单作用气动执行器一般分为常开型和常闭型。

常开型：容通气关，断气开

常闭型，通气开，断气关

A single acting pneumatic actuator opens the valve passage door when ventilated, and automatically closes when there is no air source available. A single acting pneumatic actuator relies on a spring to automatically reset and is commonly used in dangerous working conditions, such as conveying combustible gases or liquids. In the event of an emergency after losing the air source, the internal structure of the single acting pneumatic actuator can automatically reset to minimize the danger, while a double acting pneumatic actuator is generally not easy to reset. Single acting pneumatic actuators are generally divided into normally open and normally closed types.

Normally open type: Volume ventilation off, gas cut-off on

Normally closed, ventilated on, disconnected off

二、进口单作用式气动执行器工作原理

当气源压力从气口（2）进入气缸两活塞之间中腔时，使两活塞分离向气缸两端方向移动，迫使两端的弹簧压缩，两端气腔的空气通过气口（4）排出，同时使两活塞齿条同步带动输出轴（齿轮）逆时针方向旋转。在气源压力经过电磁阀换向后，气缸的两活塞在弹簧的弹力下向中间方向移动，中间气腔的空气从气口（2）排出，同时使两活塞齿条同步带动输出轴（齿轮）顺时针方向旋转。（如果把活塞相对反方向安装，弹簧复位时输出轴即变为反向旋转）

When the air source pressure enters the cavity between the two pistons of the cylinder from the air port (2), it separates the two pistons and moves them towards the ends of the cylinder, forcing the springs at both ends to compress. The air in the air chambers at both ends is discharged through the air port (4), and at the same time, the two piston racks synchronously drive the output shaft (gear) to rotate counterclockwise. After the air source pressure is reversed through the solenoid valve, the two pistons of the cylinder move towards the middle under the elastic force of the spring, and the air in the middle air chamber is discharged through the air port (2), while the two piston racks synchronously drive the output shaft (gear) to rotate clockwise. (If the pistons are installed in the opposite direction, the output shaft will rotate in the opposite direction when the spring is reset.)

三、进口单作用式气动执行器性能参数

四、单作用式气动执行器选用

选用气动执行器时，在已确定阀门的扭矩上再增加安全值，水蒸气或非润滑的液体介质增加25%安全值；非润滑的浆料液体介质增加30%安全值；非润滑的干气介质增加40%安全值；非润滑用气体输送的颗粒粉料介质增加60%安全值；对于清洁、低摩擦的润滑介质增加20%安全值（上述安全值为本公司理论推荐，仅供参考）。

单作用式执行器选用示例

当控制一个需要扭矩100Nm的蝶阀，气源压力为0.5MPa，介质为非润滑的干燥气体，考虑到安全因素，增加40%安全值等于140Nm，按单作用输出扭矩表查找弹簧复位终点得到相近扭矩148Nm，然后沿该行向左查找气源压力0.5MPa的终点扭矩158Nm，必须考虑气源压力扭矩和弹簧复位扭矩相对力平衡，再沿该行向左查找其型号和弹簧数量，选择AT145型、9只弹簧。

五、气动执行器有关数据

A）执行器的动作时间是下列条件测试；（1）常温（2）900行程（3）电磁阀4mm口径，流量为Qn400L/min   （4）管子内径8mm（5）中性干净空气（6）气源压力0.6MPa（7）执行器空载

注：在现场测试中一个或多个参数不同，动作时间会发生变化。

B）单作用重量为10根弹簧计算；需要增加或减少弹簧数量按每根弹簧重量来计算增加或减少每一台重量。