最常见的线性演员选项何时出现？

This is the first of several technical notes on the technology known as moving coil actuators. Here we provide a brief history of linear actuators used in automation — and hint at where moving coil actuators are suitable.

By Ed Neff • President |SMAC Moving Coil Actuators (MCA)

液压执行器排名第一。这些设备会产生高力，并且由于液压流体不可压缩，因此可以用作伺服设备。

That means hydraulic actuators can operate as servo actuators, which is useful in applications that need variable speed and positioning. Primary uses are in the machine tool industry, plastic processing, and off-highway equipment. Speed isn’t high. Cost for hydraulic actuation is relatively high due to the need for power units and pumps. Typical life is about 10 million cycles. Leakage of fluid is a major concern.

第二次世界大战后出现了气动执行器（和阀门）。这些设备会产生低至中力，并且相对较快。但是，由于其工作流体（空气）如何可压缩，因此气动执行器通常不被用作伺服设备，因此很难用于定位。这意味着气动圆柱体实质上提供了两个位置运动……必须手动进行调整。

Typical life is about 10 million cycles. Pneumatic actuators on their own are inexpensive. However, they do require the purchase of a compressor.

Electric actuators also emerged after World War II. The first of these devices (and many today) employ rotary motion from an electric motor that’s converted to linear motion through some mechanism — often ball screws. Rotary motors are either open-loop steppers or closed-loop servo motors … with speed and position programmable on the latter.

尽管这种几何形状损害了速度和定位精度，但可以通过宽螺栓螺距进行高速。循环寿命与气缸的寿命相当。如上所述，电动执行器首先取代了液压致动器，但由于速度精确的权衡和循环寿命，现在正面临线性电动机的直接竞争。这些设备的价格约为气缸的成本三倍。

在1980年代后期，第一个基于线性电机的执行器开始出现。这是由于高强度磁铁的发展……首先是samarium钴，然后是霓虹虫。这些DC设备包括线圈，以用磁铁移动组件的一部分。

Linear-motor actuators are servo devices with programmable position and speed capabilities. They can have a much longer life (to 100 million cycles) than air cylinders or ball screw actuators. To get relatively high speeds, the actuators need current to 5-A+ range, this being needed due to mass of the moving magnet. Force level is comparable to pneumatic devices. The price is about eight times that of pneumatic devices.

2000年,另一种th的介绍了直线电机e market — the moving-coil actuator. The development of neodymium magnets is key to this device. Moving-coil actuators are dc devices that use a series of static coils to move magnets mounted on a piston. They are servo devices that allow programmable control of position and velocity. They also allow programming of forces. Because the piston is a relatively light mass, these are the fastest linear actuators on the market.

移动线圈执行器（也称为语音线圈执行器）满足了一系列设计目标。执行器内部是产生磁场的永久磁体。移动线圈位于该领域。通过线圈的电流会产生其遍历IT及输出轴或航天飞机的遍历运动。

Just as moving magnet linear-motor actuators, moving-coil actuators also have long cycle life. Current input is in the 1.5-A range due to the low moving mass. Stroke is limited to about 500 mm. Output force is comparable to that of pneumatic actuators. Price is about two to three times that of pneumatic actuators — and continues to drop.

Electric actuators have slowly replaced hydraulic actuators in about 70% of applications — mostly for reasons related to cost, cycle life, and performance.

气动执行器很难用其他线性技术取代，这主要是因为它们的前期成本低。但这正在改变。考虑电子组件，其中气动线性致动器几乎被球螺钉或移动线圈设备完全替换。在该行业中，循环寿命和速度都至关重要 - 而且价格并不那么重要。现在，包装行业发生的类似变化。

在这里，所有三个电动设计（球螺钉，移动磁铁和移动线圈）都在代替气动执行器。关键原因是消除压缩机，更高的周期寿命，可编程转换和更高的速度。即便如此，成本还是一个关键……因此，将需要低成本的电动执行器来完全转变该行业。

That leads us to moving-coil actuators — which satisfy all these design objectives … especially useful for new packaging-machine builds. Within the actuator are permanent magnets generating a magnetic field; a moving coil resides in that field. Passing current through the coil generates traverse motion of it and the output shaft or shuttle. The force of that output is proportional to the coil’s turns ad the magnetic flux within the actuator (both constants) as well as the current. Therefore, increasing current through the coil increases the output force. Just consider how this functionality helps moving-coil linear cylinders outperform pneumatic cylinders on a number of fronts.

FEATURE	语音线性圆柱体	PNEUMATIC CYLINDER
位置验证	Interface visually displays rod’s exact position for setup	罗德未知的位置；必须在视觉上调试
Durability	More than 200 million cycles	10 to 20 million cycles
Configurability	速度，位置和力量	None — limited to mechanical adjustment
Energy consumption	Low (24/48 V) V/A (1.7 A peak)	空气供应和电力的昂贵需求
Noise	Less than 55 dB	通常超过85 dB
可重复性	±1 msec cycle-time variance	20毫秒循环时间差异
Validation	Encoder feedback and full control of move parameters	传感器或开关无法控制移动，只有限制
所有权成本	Initial price; no maintenance	定期更换和调整；需要压缩机，阀门，管道