风阀执行器——电动和气动有什么区别？（中英文）

电动和气动执行器通过控制风门和阀门在 HVAC 系统中发挥着核心作用，但它们的工作方式有着根本的不同。电动执行器响应控制信号（通常为2至10伏直流电或4至20毫安）来精确调整其位置。相反，气动执行器依靠压缩空气压力（也称为空气信号）来工作。这需要专用的供气管线和配套设备。虽然气动系统曾经被广泛使用，但由于电动执行器具有更高的精度、更容易的安装和流线型设计，它已经成为标准。例如，Belimo 的直接耦合电动执行器无需气管、压缩机、传感器或定位器，而这些是气动装置中必不可少的组件。

Electric and pneumatic actuators play central roles in HVAC systems by controlling dampers and valves, yet they differ fundamentally in how they operate. Electric actuators respond to a control signal, typically between 2 and 10 volts DC or 4 to 20 milliamps, to adjust their position precisely. In contrast, pneumatic actuators rely on compressed air pressure to function, also known as an air signal. This requires dedicated air supply lines and supporting equipment. Although pneumatic systems were once widely used, electric actuation has become the standard thanks to its enhanced precision, easier installation, and streamlined design. Belimo’s direct-coupled electric actuators, for example, eliminate the need for air lines, compressors, transducers, or positioners, components that are mandatory in pneumatic setups.

什么是滞后？

What is hysteresis?

滞后是指控制信号与执行器实际位置之间的差异，具体取决于运动方向。在气动系统中，连杆、阀杆卡紧、密封件和其他机械阻力产生的内部摩擦力都会造成这种影响。由于气动控制信号也充当动力源，它必须超过目标值才能克服阻力，这通常会导致过冲。当信号反向时，它必须低于弹簧力才能启动运动，这也会导致位置误差。

Hysteresis refers to the difference between the control signal and the actual position of the actuator depending on the direction of movement. In pneumatic systems, internal friction from linkages, stem binding, seals, and other mechanical resistance contributes to this effect. Because the air control signal also acts as the power source, it must exceed the target to overcome resistance, often leading to overshoot. When the signal reverses direction, it must drop below the spring force to initiate movement, also contributing to positional error.

为什么电动执行器比气动执行器更精确？

Why is electric actuation more accurate than pneumatic actuation?

像Belimo这样的电动执行器专为精确定位而设计，其正常滞后仅为1%。Belimo通过内部反馈电路持续比较输入信号与实际轴位置，将滞后降至最低。相比之下，气动执行器在 5 PSI 的弹簧范围内通常表现出约 1.5 PSI 的滞后。额外的机械负载会加剧这种影响，进一步降低精度。

Electric actuators like Belimo’s are designed for precision positioning, with a normal hysteresis of just 1%. Belimo minimizes this through internal feedback circuits that continuously compare the input signal to the actual shaft position. Pneumatic actuators, by contrast, typically exhibit around 1.5 PSI of hysteresis over a 5 PSI spring range. Additional mechanical loading increases this effect, further reducing accuracy.

与气动混合执行器相比，Belimo电动执行器的分辨率是多少？

What is the resolution of Belimo electric actuators compared to pneumatic hybrids?

Belimo执行器的最小分辨率为 160:1，这使得它们能够响应控制信号的微小变化。典型的 DDC 控制器可以输出 0.1 VDC 的分辨率，而 Belimo 的内部电路可以达到这一水平。气动混合系统（包括 DDC 控制器、传感器、定位器和执行器）在实际应用中只能达到约 20:1 的分辨率。

Belimo actuators have a minimum resolution of 160:1, allowing them to respond to very small changes in the control signal. A typical DDC controller can output with 0.1 VDC resolution, and Belimo’s internal circuitry can match that. Pneumatic hybrid systems, which include a DDC controller, transducer, positioner, and actuator, can only achieve about 20:1 resolution in practice.

为什么气动执行器无法始终准确响应控制信号？

Why don’t pneumatic actuators always respond predictably to the control signal?

气动执行器通常并非仅根据控制信号进行定位。最终位置取决于空气信号力、弹簧力、阻尼器负载和阻力的净效应。这些相互作用力可能会导致有效弹簧行程发生显著变化。例如，如果阻尼器负载作用方向与空气信号方向相同，那么弹簧行程范围为 8 至 13 PSI 的执行器实际上可能在 4 PSI 时就开始移动。这会导致定位不一致，控制分辨率降低。

Pneumatic actuators often do not position based solely on the control signal. The final position depends on the net effect of air signal force, spring force, damper load, and resistance. These interacting forces can cause significant shifts in the effective spring range. For example, an actuator with an 8 to 13 PSI spring range could actually begin to move at 4 PSI if the damper load acts in the same direction as the air signal. The result is inconsistent positioning and reduced control resolution.

定位器能提高气动执行器的精度吗？

Can positioners improve the accuracy of pneumatic actuators?

可以，但作用有限。单台气动执行器的精度可能在+/-15%。使用定位器后，精度可以提高到5%左右，但这会增加复杂性和维护成本。机械定位器会随着时间的推移，由于磨损、弹簧疲劳和校准漂移而性能下降。信号链中的每个组件，包括传感器、定位器和执行器，都会引入误差。随着时间的推移，即使经过精心设置，精度也会持续下降。

Yes, but only to a limited extent. A pneumatic actuator alone may have accuracy of +/-15%. With a positioner, this can improve to about five percent, but this comes with added complexity and maintenance. Mechanical positioners degrade over time due to wear, spring fatigue, and calibration drift. Each component in the signal chain, including the transducer, positioner and actuator, introduces error. Over time, even with careful setup, accuracy continues to decline.

执行器性能如何影响温度控制和能源效率？

How does actuator performance affect temperature control and energy efficiency?

精确的执行器直接影响热舒适度和能源效率。具有紧密滞后和高分辨率的电动执行器能够紧密跟踪控制信号，将温度保持在允许范围内，并最大限度地减少能源浪费。气动执行器本身存在精度问题，容易出现位置漂移，尤其是在扭矩负载变化或风速较高的情况下。这会导致温度和气流控制出现过冲、欠冲和不稳定的情况。

Precision actuation directly impacts thermal comfort and energy efficiency. Electric actuators with tight hysteresis and high-resolution track the control signal closely, keeping temperatures within range and minimizing energy waste. Pneumatic actuators, with their inherent inaccuracy, tend to hunt for position, especially under varying torque loads or high air velocities. This results in overshoot, undershoot, and instability in temperature and airflow control.

电动执行器是否比气动系统更可靠？

Are electric actuators more reliable than pneumatic systems over time?

是的。虽然气动执行器本身机械性能可能非常耐用，但其周围的组件（例如传感器、压缩机、干燥器、过滤器和配件）可能会引发多个故障点。气动系统的维护可能涉及多达 23 个组件。Belimo的电动系统仅需三个组件：线路、DDC 面板和变压器。Belimo电子执行器预计至少可完成 60,000 个全行程循环，并且几乎无需维护，使用寿命可达 15 至 20 年。在两年的保修期内，Belimo执行器的故障率仅为 0.3%。

Yes. While pneumatic actuators themselves may be mechanically durable, the surrounding components, such as transducers, compressors, driers, filters, and fittings, can introduce multiple points of failure. Maintenance for a pneumatic system can involve up to 23 components. Belimo’s electric systems require just three: wiring, the DDC panel, and a transformer. Belimo electronic actuators are expected to last a minimum of 60,000 full stroke cycles, and 15 to 20 years with minimal maintenance. Belimo actuators have a failure rate of just 0.3 percent over a 2-year warranty period.

气动执行器有哪些缺点？

What are the disadvantages of pneumatic actuators?

气动执行器通常在需要精确中间定位的调节控制应用中表现不佳。由于磁滞和内部摩擦，气动执行器只有其全行程的 20% 到 50% 可用于可靠控制。此外，它们还依赖于压缩机、传感器和气站等外部组件，这会带来额外的维护需求和潜在的故障点。

Pneumatic actuators typically perform poorly in modulating control applications that demand accurate intermediate positioning. Due to hysteresis and internal friction, only 20 to 50 percent of a pneumatic actuator’s full stroke may be usable for reliable control. They also rely on external components like compressors, transducers, and air stations, which introduce additional maintenance requirements and potential points of failure.

电动执行器有哪些缺点？

What are the disadvantages of electric actuators?

在极端高负载或特定工艺应用中，电动执行器可能需要额外的保护或设计考虑，而这些应用传统上通常使用快速动作的气动装置。但对于绝大多数暖通空调 (HVAC) 应用而言，电动执行器不仅能满足性能要求，还能提供卓越的控制灵活性和一致性。

Electric actuators may require additional protection or design considerations in extreme high-load or process-specific applications where fast-acting pneumatic devices have traditionally been used. But for the vast majority of HVAC applications, electric actuation not only meets performance requirements but also delivers superior control flexibility and consistency.

电动执行器和气动执行器的成本差异是什么？

What are the cost differences between electric and pneumatic actuation?

Belimo电动执行器的初始安装成本通常较低。相比弹簧复位阻尼器的完整配置，如果将传感器、定位器、人工和共用气站基础设施的成本计算在内，电动系统的成本低于气动系统。随着时间的推移，这种差异会越来越大。气动系统需要持续维护更多组件，而Belimo的电动解决方案仅涉及接线、DDC面板和变压器。由于无需定期维护，并且通过更佳的控制实现更高的效率，电动执行器的生命周期成本显著降低。

Initial installation costs are typically lower for Belimo electric actuators. When comparing a complete setup for a spring return damper, electric systems are less expensive than pneumatic systems once the costs of transducers, positioners, labor, and shared air station infrastructure are included. The difference becomes even greater over time. Pneumatic systems require ongoing maintenance across many more components, while Belimo’s electric solution involves only wiring, a DDC panel, and a transformer. With no recurring service needs and higher efficiency through better control, the life cycle cost of electric actuation is significantly lower. 

气动和电动哪个更好？

Which is better, pneumatic or electric?

在大多数暖通空调 (HVAC) 应用中，电动执行器可提供更高的精度、可靠性、分辨率和能效。虽然气动系统可以在精度要求较低的简单双位控制场景中提供更高的扭矩，但电动执行器通常能够满足这些扭矩需求，同时提供卓越的一致性和长期成本节约。对于需要精确定位和重复性的调节控制，电动执行器明显更适合，并且避免了气动系统常见的漂移、滞后和振荡现象。在寒冷的环境中，由于气管和气动元件容易冻结，电动执行器更适合，尤其是在需要位置反馈的情况下。Belimo提供故障安全和非故障安全型号来满足这些需求。

Electric actuation offers better accuracy, reliability, resolution, and energy efficiency in most HVAC applications. While pneumatic systems can deliver higher torque in simple two-position control scenarios where precision is less critical, electric actuators often meet those torque demands while providing superior consistency and long-term cost savings. For modulating control, where accurate positioning and repeatability are required, electric actuation is a significantly better fit and avoids the drift, hysteresis, and hunting associated with pneumatic systems. In cold ambient environments, where air lines and pneumatic components are prone to freezing, electric actuation is the better fit, especially when position feedback is required. Belimo offers both fail-safe and non fail-safe models to meet these needs.