电动线性执行器的类型介绍及选型指南（连载二）

需要了解的术语

Terms to Know About

这里介绍了一些描述电动线性执行器的的术语。

Here we define some of the most prevalent terms describing electric linear actuators.

静态负载能力

Static Load Capacity

电动线性执行器的静态负载是指当所连接的电机处于滑行模式时，移动执行器活塞所需的最小外力。在滑行模式下，电机处于空转状态，没有驱动电压，电机端子处于开路状态（未短接）。

最大静态负载规格对于大多数应用至关重要，因为它决定了电动线性执行器在驱动电源关闭或断开时的保持力。如果应用需要将负载保持在适当位置，例如打开的舱口或升起的面板，则执行器的静态负载必须大于舱口或面板施加在活塞上的力。

当外部负载推动或拉动电动线性执行器活塞时，它还必须移动整个执行器组件，包括活塞、丝杠、齿轮系和电机轴。丝杠和齿轮系的特性会显著影响静态负载额定值。

大多数执行器的丝杠类型为 ACME 或滚珠丝杠。一般而言，ACME 螺纹的效率低于滚珠丝杠，但其抗反向驱动能力更强。因此，ACME 螺纹具有更高的静态负载能力。此外，特定的螺母材料（例如金属或聚合物）以及任何添加剂润滑剂的粘度也会影响丝杠设计的反向驱动阻力。

如上文线性执行器配置部分所述，电机相对于活塞和丝杠的不同方向会影响齿轮系的选择。直角配置通常利用蜗轮将扭矩从电机轴以 90 度角传递到丝杠。蜗轮往往具有自锁功能，反向驱动效率非常低。因此，垂直电动线性执行器往往能够承受更高的静态负载。

齿轮比等因素也会影响线性执行器的静态负载。高齿轮比会通过降低速度来放大扭矩，并具有较高的反向驱动阻力，最终导致更高的静态负载。

The static load of an electric linear actuator is the minimum external force required to move the actuator piston when the attached electric motor is in coast mode. In coast mode, the motor is idle with no drive voltage, and the motor terminals are in an open circuit (not shorted together).

The maximum static load specification is essential for most applications because it determines the electric linear actuator’s holding strength when the drive power is off or disconnected. If an application includes keeping a load in position, such as an open hatch or raised panel, then the static load of the actuator must be greater than the force placed upon the piston by the hatch or panel.

When an external load pushes or pulls an electric linear actuator piston, it must also move the entire actuator assembly, including the piston, lead screw, gear train, and motor shaft. The lead screw and gear train properties significantly affect the static load rating.

Most actuator’s lead screws are either an ACME or Ball screw type. In general, ACME threads are lower efficiency than Ball screws but offer much higher resistance to back driving. Thus, ACME threads offer a higher static load capacity. Further, the specific nut material, for example, metal or polymer, and the viscosity of any additive lubrication will also influence the back-driving resistance of the lead screw design.

As described above in the linear actuator configuration section, different orientations of the motor relative to the piston and lead screw influence the selection of the gear train. Right angle configurations generally utilize a worm gear to transfer torque 90 degrees from the motor shaft to the lead screw. Worm gears tend to be self-locking with a very low reverse drive efficiency. Thus, perpendicular electric linear actuators tend to support a higher static load.

Factors such as the gear ratio will also affect linear actuators’ static load. High gear ratios amplify torque by reducing speed and will have high resistance to back driving and contribute to a higher static load.

动态负载能力

Dynamic Load Capacity

电动线性推杆的动态负载是指电动机在最大电压和峰值电流驱动下，推杆活塞产生的峰值力（推力或拉力）。与上述静态负载类似，活塞产生的力必须从电动机开始，经齿轮系传递至丝杠，最终通过连接在活塞上的驱动螺母，穿过整个推杆组件。该传递链中的每个环节都会影响传递到活塞的力的大小。

电动机驱动轴产生的扭矩等于通过电动机电枢驱动的电流乘以电动机常数。电流越大，扭矩越大。电源输送到电动机的电流量与驱动电压成正比，电压越高，电流也就越大。因此，电压越高，电流也就越大，扭矩也就越大。

对于任何给定的驱动电压，产生的电流（以及扭矩）是电动机绕组内阻和电动机旋转时产生的反电动势电压的函数。内阻是一个固定值，反电动势会随着电动机转速的增加而增大。随着电机每分钟转速 (RPM) 和反电动势 (EMF) 的增加，输送到电机的电流会减小。因此，对于任何给定的驱动电压，在电机刚开始旋转时产生的电流和扭矩最大。随着电机转速的增加，电流和扭矩会减小，直到电机达到平衡状态，此时扭矩刚好足以驱动负载并保持恒定速度。

直流电机的驱动轴直接连接到大多数执行器的齿轮系输入轴。齿轮系是由两个或多个串联的齿轮组成，齿轮系的齿轮比是从动齿轮与驱动齿轮齿数之比。根据齿轮传动定律，输出扭矩与输入扭矩之比等于齿轮比，输出速度与输入速度之比是齿轮比的倒数。例如，当齿轮比为 2 时，齿轮系的输出主轴将以输入主轴一半的速度运转，产生的扭矩是输入主轴的两倍。大多数电动线性执行器的齿轮比大于 1，以有效降低高速直流电机的速度，从而为丝杠提供更大的扭矩。因此，经验法则是，必须在速度和强度之间做出取舍。高速线性执行器通常比低速线性执行器输出的扭矩更小。

最后，丝杠的螺纹在驱动螺母内旋转，迫使其伸缩连接的执行器活塞，从而将旋转扭矩转换为线性力。在这种情况下，螺母的类型（ACME 或滚珠丝杠）、螺母材料以及润滑剂将决定传输到活塞的动力效率，而不会因摩擦而损失。

The dynamic load of an electric linear actuator is the peak force (push or pull) delivered by the actuator piston when the electric motor is driven at maximum voltage and peak current. Like the static load above, the force produced at the piston must traverse the entire actuator assembly from the electric motor, through the gear train to the lead screw, and finally through the drive nut attached to the piston. Each interface in this chain affects the magnitude of the force delivered to the piston.

The torque developed at the motor drive shaft is a product of the electric current driven through the motor armature times the motor constant. Higher currents generate greater torque. The amount of current delivered to the motor from the power supply is proportional to the drive voltage, where higher voltages will have higher currents. Thus, higher voltages drive higher currents and develop greater torques.

For any given drive voltage, the current (and thus torque) produced is a function of the internal resistance of the motor windings and the back-EMF voltage developed by the motor as it rotates. The internal resistance is a fixed value and the back-EMF increases with motor velocity. As the motor’s revolutions per min (RPM) and back-EMF increase, the current delivered to the motor decreases. Thus, for any given drive voltage, the greatest current and torque are produced when the motor first begins to rotate. As the motor velocity increases, the current and torque reduce until the motor reaches equilibrium, and the torque is just sufficient to drive the load and maintain a constant velocity.

The DC motor drive shaft connects directly to most actuators’ gear train input shaft. A gear train is two or more gears connected in series, and the train’s gear ratio is the ratio of the number of teeth in the driven gear versus the driving gear. According to the law of gears, the ratio of output torque to input torque is equal to the gear ratio, and the ratio of output velocity to input velocity is the inverse of the gear ratio. So, for example, the output spindle of a gear train with a ratio of 2 will run at half the velocity of the input spindle and generate twice the torque as the input spindle. Most electric linear actuators have a gear ratio greater than one to effectively reduce the velocity of the high-speed DC motor in exchange for greater torque delivered to the lead screw. Thus, the rule of thumb is you must trade speed or strength. Fast linear actuators will generally deliver less torque than slow linear actuators.

Finally, the lead screw converts from rotational torque to linear force as its threads rotate within the drive nut forcing it to extend or retract the attached actuator piston. In this case, the type of nut (ACME or ball screw), the nut material, and any lubricants will determine the efficiency of power transmitted to the piston and not lost to friction.

占空比

Duty Cycle

电动线性执行器的额定占空比是指为避免加速磨损和损坏而设定的最大驱动频率。制造商将占空比定义为工作时间与关断时间之比的百分比。例如，运行 30 秒，停止 90 秒，则占空比为 25%。采用耐用性较差的材料制成的廉价线性执行器通常会指定较低的占空比，以避免损坏电机绕组或齿轮。

在建议的占空比范围内运行有助于避免内部组件过热，过热会导致内部组件过早磨损。尤其是齿轮、轴承、衬套和电机绕组最容易过热。

由于占空比规格限制了累积的热量和磨损，因此应将其视为设计指南，而非硬性限制。外部环境因素也是管理线性执行器热量的重要因素。例如，在炎热的室外环境中以峰值动态负载运行，可能需要使用低于制造商规格的最大占空比。另一方面，在低温室内环境中峰值动态负载下运行良好可能允许在制造商的占空比规格内运行。

An electric linear actuator’s rated duty cycle is the maximum frequency of drive time to avoid accelerated wear and damage. Manufacturers specify duty cycle as a percentage of the ratio of on-time to off-time. For example, running for 30 seconds and resting for 90 seconds is a 25% duty cycle. Cheap linear actuators built from less durable materials will often specify a low duty cycle to avoid damage to the motor windings or gears.

Operating within the recommended duty cycle will help avoid overheating the internal components, which can lead to premature wear of internal components. In particular, gears, bearings, bushing, and motor windings are the most vulnerable to overheating.

Because duty cycle specifications limit accumulated heat and wear, they should be considered a design guideline, not a hard limit. External environmental factors are also a significant factor in managing linear actuator heat. For instance, operating at peak dynamic load in a hot outdoor environment may dictate a maximum duty cycle below the manufacturer’s specification. While on the other hand, running well under peak dynamic load in a low-temperature indoor environment may allow you to operate over the manufacturer’s duty cycle specification.

IP 防护等级系统

IP rating system

IEC 605529 定义的侵入防护 (IP) 等级系统根据机械和电气外壳是否符合标准防护等级，对人身意外接触和灰尘、水等有害物质的侵入进行分类。IP 等级使消费者能够以标准格式了解产品提供的具体防护等级，并选择能够适应其预期工作条件的产品。

IP 代码格式以前缀 IP 开头，后跟两位数字，最多可添加两位字母，用于指定防护等级。IP 等级的第一位数字始终表示对固体颗粒侵入的防护。数值越大，表示对较小颗粒的防护等级从 1 级（定义为对较大身体部位的防护）到 6 级（定义为防尘外壳）。

环境中的灰尘和其他颗粒可能很低（例如在办公室环境中），也可能很密集（例如在机械加工或农业环境中）。对于低尘环境，选择 IP 固体防护等级 5（IP5x）即可；对于高尘环境，请选择等级 6（IP6x）的执行器。

第二位数字表示产品的防液体侵入防护等级。与第一位数字类似，第二位数字越高，表示在温度和压力升高的情况下，防护等级也越高。防护等级范围从1级（定义为防垂直滴落）到9K级（定义为防强力高温水射流）。

与防尘一样，所需的液体侵入防护等级也因预期工作环境而异。例如，在室内办公环境中操作时，可能只需要4级（IPx4）防护等级即可保护执行器免受偶尔的意外溢漏。在工业工厂环境中操作时，可能需要5级（IPx5）防护等级，以防清洁喷射。同时，在食品加工厂操作时，可能需要9K级（IPx9K）防护等级，以防强力消毒喷雾。

最常见的两种电动线性推杆IP等级是IP54和IP66。IP54等级的电动线性推杆适用于低尘、干燥的环境，在这些环境中，推杆可能会被溅到，但不会经常被淋湿。带有 IP66 的执行器非常适合高尘户外潮湿环境，包括雨水和喷射水，但不包括浸没。

The Ingress Protection (IP) rating system, defined in IEC 605529, classifies mechanical and electrical enclosures by their conformance to standard protection categories against accidental human contact and intrusion of harmful material such as dust and water. IP ratings allow consumers to understand the specific levels of protection a product provides in a standard format and to select products that will survive their intended operating conditions.

The IP codes format begins with the prefix IP followed by two digits and optionally up to two letters to specify the levels of protection. The first digit of an IP rating always specifies protection against solid particle intrusion. Greater values indicate protection against smaller particles from level 1, defined as protection from large body parts to level 6, defined as a dust-tight enclosure.

Dust and other particles in the environment may be low such as in an office environment, or dense such as in a machining or agricultural setting. For low dust environments, selecting an IP solid protection rating of 5 (IP5x) is sufficient; for dense dust environments, select an actuator with a rating of 6 (IP6x).

The second digit specifies the product’s protection against liquid ingress. Similar to the first digit, higher values of the second digit indicate increasing levels of protection at increasing temperature and pressure. Protection ranges from level 1, defined as protection from verticle drips to level 9K, defined as protection from powerful high-temperature water jets.

Like dust, the required liquid ingress protection varies with the intended operating environment. Operation in an indoor office environment, for example, may only require level 4 (IPx4) to protect the actuator from occasional accidental spills. Operation in an industrial factory environment may call for level 5 (IPx5) protection from cleaning jets. At the same time, operations in a food processing plant may require a level 9K (IPx9K) to protect from powerful sanitizing sprays.

Two of the most common electric linear actuator IP ratings are IP54 and IP66. Electric linear actuators rated IP54 are suitable for low dust, dry environments where the actuator may be splashed but not routinely wet. Actuators carrying an IP66 are ideal for high dust outdoor wet environments, including rain and jets but not submersion.

电动线性推杆的优缺点

Pros and cons of Electric Linear Actuators

与所有技术一样，与气动和液压等其他推杆技术相比，电动线性推杆也有其优缺点。

As with all technologies, there are pros and cons to the use of electric linear actuators when compared with other actuator technologies such as pneumatic and hydraulic.

优点

• 电动线性推杆易于部署且自成一体。它们只需极少的支撑系统，例如压缩空气或液压油处理。

• 许多电动线性推杆具有较高的静态力，即使在没有动力的情况下也能将负载固定到位。

• 电动线性推杆比液压推杆更清洁，防护等级达到 IP66 或更高，适用于潮湿、消毒的环境。

• 电动线性推杆与功能强大的控制器搭配使用时，灵活性极佳，可实现精确的位置、速度和力控制。

• 电动线性推杆使用寿命长，几乎无需维护。

Pros

• Electric linear actuators are easy to deploy and self-contained. They require minimal supporting systems such as pressurized air or hydraulic fluid handling.

• Many electric linear actuators offer high static force, making them suitable for holding loads in place even when not powered.

• Electric actuators are much cleaner than their hydraulic counterparts and, when rated IP66 or higher, are suitable for wet, sanitized environments.

• Electric linear actuators are incredibly flexible when paired with a capable controller, delivering precision position, velocity, and force control.

• Electric linear actuators have a long operating lifetime requiring little or no maintenance.

缺点

• 许多电动线性执行器需要较低的工作占空比，设计人员必须考虑工作环境条件。他们必须确保执行器的工作频率和负载不会导致其过热和过早失效。

• 过流情况可能会在电刷、换向器或电枢中造成短路或断路，从而损坏电动线性执行器内的直流电机。例如，设计人员必须注意确保失速设备不会过度驱动。直流电机突然急停也会产生较大的电气瞬变，这可能会损坏直流电机。

• 虽然电动线性执行器适用于各种环境，但只有额定功率合适的执行器型号才能在易燃区域运行，因为火花可能会引起点火。

Cons

• Many electric linear actuators require low operating duty cycles, and the designer must consider the operating environmental conditions. They must ensure the actuator’s operating frequency and load do not cause it to overheat and fail prematurely.

• Over-current conditions may damage the DC motor within electric linear actuators by creating a short or open circuit in the brush, commutator, or armature. Designers must take care, for instance, to ensure that a stalled device is not over-driven. Exposing the DC motor to sudden hard stops will also create large electrical transients, which may damage the DC motor.

• While electric linear actuators are suited to various environments, only properly rated actuator models can be operated in flammable areas where sparks may cause ignition.

如何为项目选择合适的电动线性推杆

How to Choose the Right Electric Linear Actuator for Your Project

选择电动线性推杆时，必须考虑多项设计要求和推杆性能规格。以下列表列出了一些最常见的设计考虑因素，可供参考。

• 确定所需的动态力：这是移动物体或目标结构所需的力。在预期的力需求基础上增加 50% 的裕度，以指定最小动态力。

• 确定所需的静态力：执行器在必须支撑负载的伸展位置是否会处于闲置状态？请考虑静止负载将传递给线性执行器活塞的力。选择静态力至少比预估的保持力高 50% 的执行器。

• 确定总移动距离：测量物体在线性执行器连接点处移动的总距离。同样，在指定线性执行器的最小伸展距离时，请在位移基础上增加 10% 或 20% 的裕度。

• 确定所需的速度：首先确定完成移动所需的时间。然后将移动距离除以移动时间，即可计算出所需的移动速度。同样，增加 10% 到 20% 的裕度，以设置执行器的最小速度规格。在审查执行器规格时，最大速度会随动态力而变化。在确定预期执行器速度时，请使用计划的动态力。

• 定义占空比：确定执行器运动时间的百分比。此外，还要确定执行器是在低温至室温还是高温下工作。如果在室温或更低温度下工作，则计划以不超过指定执行器最大占空比的速率运行。如果在高温下工作，则计划以低于执行器最大占空比的速率运行。可能需要购买执行器并在预期环境中进行评估，以确保其在计划的占空比下不会过热。

• 考虑可用电源：确定打算与电动线性执行器配对的驱动器或电源的可用电压和最大电流。确保线性执行器的电压规格匹配。最常见的电动线性执行器电压为 6 伏、12 伏和 24 伏。确保线性执行器的峰值电流消耗（也称为失速电流）小于最大电源电流。

• 定义可用空间：设计空间受限吗？是否需要窄型直列式执行器以避免在移动时撞到物体？空间是否狭窄，需要平行或垂直配置吗？

When selecting an electric linear actuator, you must consider several design requirements and actuator performance specifications. The list below is a good starting point for the most common design considerations.

• Determine the Required Dynamic Force: This is the force required to move the object or target structure. Add a 50% margin above your anticipated force requirement to specify the minimum dynamic force.

• Determine the Required Static Force: Will the actuator sit idle in an extended position where it must support a load? Consider the force the resting load will transfer to the linear actuator piston. Select an actuator with a static force at least 50% greater than your estimated holding force.

• Define the Total Movement Distance: Measure the total distance the object will move at the point where the linear actuator will attach. Again, add a 10% or 20% margin to the displacement when specifying the minimum linear actuator extension.

• Define the Required Speed: Start with the desired time to complete the movement. Then divide the movement distance by the movement time to calculate the desired movement velocity. Again, add a margin of 10% to 20% to set your minimum actuator speed specification. When reviewing actuator specifications, the maximum speed will vary with the dynamic force. Use your planned dynamic force when determining the expected actuator speed.

• Define the Duty Cycle: Determine what percentage of the time the actuator will be in motion. Also, determine if the actuator will operate at a low to room temperature or an elevated temperature. If at room or lower temperature, plan to run at but not exceeding the specified actuator maximum duty cycle. If operating at a high temperature, plan to operate at less than the actuator’s maximum duty cycle. You may need to purchase and evaluate the actuator in your intended environment to ensure it does not overheat under your planned duty cycle.

• Consider the Available Power Source: Determine what voltage and maximum current are available from the driver or power supply you intend to pair with the electric linear actuator. Ensure the linear actuator voltage specification matches. The most common electric linear actuator voltages are 6, 12, and 24 volts. Be sure that the peak current consumption of the linear actuator, also known as the stall current, is less than the maximum supply current.

• Define the Available Space: How space-constrained is your design? Do you need a narrow inline actuator to avoid hitting objects while moving? Is your space short, and do you need a parallel or perpendicular configuration?

如何控制电动线性推杆

How to Control an Electric Linear Actuator

已经分析了设计规格，并确定了首选线性推杆的尺寸和配置。现在，将如何控制它的启动和停止？需要精确的运动曲线还是一定程度的简单运动？是否需要同步两个或多个推杆来实现升降或推动？以下是一些最常见的电动线性推杆控制方法。

So, you’ve analyzed your design specifications and have determined the size and configuration of your preferred linear actuator. Now, how are you going to control it to start and stop? Do you need a precise motion profile or simple motion to an extent? Do you need to synchronize two or more actuators to lift or push? Here are some of the most common methods of electric linear actuator control.

固定内部限位开关

Fixed Internal Limit Switches

一些电动线性执行器在其最小和最大伸展位置嵌入了限位开关。当活塞完全伸展或缩回时，这些开关会切断直流电机的电源，避免损坏内部组件。因此，带有内部限位开关的线性执行器可以直接由直流电源供电，电压等于或低于最大额定工作电压，并在完全打开或关闭时自动停止。仍然需要一种切换电压极性的方法来控制执行器的伸展或缩回。

Some electric linear actuators have embedded limit switches at their minimum and maximum extension. These switches will remove power from the DC motor and avoid damage to the internal components when the piston reaches full extension or retraction. Thus, linear actuators with internal limit switches can be powered directly from a DC supply at or below the maximum rated operating voltage and automatically stopped when fully open or closed. You will still need a means of switching the polarity of the voltage to command the actuator to extend or retract.

可调式内部限位开关

Adjustable Internal Limit Switches

可调式内部限位开关与固定式内部限位开关类似，不同之处在于用户可以更改开关的位置。限位开关的移动通常通过松开前限位开关或后限位开关上的固定螺钉，将其滑动到新位置，然后拧紧螺钉以夹紧开关来实现。虽然可以找到带有可调式限位开关的线性执行器，但它们并不普及，并且会限制在选择力度、速度和占空比时的选项。

Adjustable internal limit switches are similar to fixed internal limit switches, except that the user can change the location of the switch. Limit switches typically move by loosening a set screw on the front or rear limit switch, sliding it to a new location, and tightening the screw to clamp the switch. While you can find linear actuators with adjustable limit switches, they are not widely available and will limit your options when selecting force, speed, and duty cycle.

外部限位开关

External Limit Switches

可以连接外部限位开关，以便在电机到达所需位置时断开电机电源。例如，可以在外壳上安装一个开关，用于检测面板是否完全关闭。连接限位开关时，必须确保有单独的电路来反向驱动执行器，因为执行器静止后，限位开关仍将保持断开状态。

It is possible to wire external limit switches to disconnect motor power when reaching the desired position. For instance, you might install a switch on the casing to detect that a panel has closed fully. When wiring limit switches, you must ensure a separate circuit is available to drive the actuator in the reverse direction because the limit switch will remain open after the actuator comes to rest.

瞬时开关和摇臂开关

Momentary and Rocker Switches

无论是否决定使用限位开关，每个设计都需要一种方法来开启和关闭线性执行器直流电机，并通过反转电压极性来切换行进方向。一种简单的电源控制方法是在电源和线性执行器之间连接一个开关。

选择开关时，请确保其最大电压和电流额定值大于线性执行器失速时的驱动电压和峰值驱动电流。与线性执行器的规格一样，选择额定值大于预期最大工作条件的开关，以便留出足够的余量来应对温度等外部变量。

为了在伸缩方向上驱动电动线性执行器，需要一个能够在开关切换时将电源电压以正向和反向连接到直流电机端子的开关。为此，请选择双刀双掷 (DPDT) 开关配置。DPDT 开关提供了一条将电源以正向或反向连接到直流电机的路径。开-关-开类型在开关掷的中间提供了一个关闭位置，以断开线性执行器的电源并将其关闭。

Whether you decide to use limit switches or not, every design needs a means of turning the linear actuator DC motor on and off and reversing the voltage polarity to switch the direction of travel. A straightforward power control method is to wire a switch between the power supply and the linear actuator.

When selecting a switch, ensure its rating for maximum voltage and current is greater than the linear actuator drive voltage and peak drive current when stalled. As with the linear actuator specifications, select a switch with ratings greater than your anticipated maximum operating conditions to provide a margin that will cover external variables such as temperature.

To drive an electric linear actuator in the extend and retract directions, you will need a switch that can connect the power supply voltage to the DC motor terminals in both forward and reverse polarities as the switch toggles. For this purpose, select a double pole double throw (DPDT) On-Off-On configuration. The DPDT switching provides a path to connect the power supply to the DC motor in either the forward or reverse polarity. The On-Off-On style provides an off position in the middle of the switch throw to disconnect the power supply from the linear actuator and turn it off.

自动控制系统

Automated Control Systems

虽然基本开关提供了一种快速而直接的线性执行器控制方法，但它们也存在一些明显的缺点。首先，使用开关时，电机要么打开，要么关闭。这意味着在开启和关闭之间的快速转换可能会产生强大的加速度和冲击脉冲，从而可能损坏直流电机或移动负载。其次，没有办法改变线性执行器的速度来应对可变负载或同步两个或多个串联工作的线性执行器。

出于这些原因，许多设计师采用智能运动控制器，例如 ACT-U8 DC-112。DC-112 使用实时位置和力反馈来改变高速脉宽调制 (PWM) 电机驱动，从而提供精确的执行器轨迹控制。使用像 DC-112 这样的电动线性执行器控制器，可以快速创建包含多个路点和速度的详细运动序列的解决方案，并同步两个或移动线性执行器以进行协调的多轴运动。

While basic switches provide a quick and straightforward way to control linear actuators, they have some significant drawbacks. First, with a switch, the motor is either on or off. That means the rapid transition between on and off may generate powerful acceleration and jerk impulses that may damage the DC motor or the moving load. Second, there is no method of varying the speed of the linear actuator to account for variable loads or to synchronize two or more linear actuators working in tandem.

For these reasons, many designers employ smart motion controllers such as the ACT-U8 DC-112. The DC-112 delivers precise actuator trajectory control using real-time position and force feedback to vary a high-speed pulse-width modulated (PWM) motor drive. Using electric linear actuator controllers like the DC-112 allows you to quickly create solutions with detailed motion sequences involving multiple waypoints and velocities and synchronize two or move linear actuators to move in coordinated multi-axis motion.

常见问题解答

FAQS

以下是一些关于电动线性推杆选型和使用的常见问题。

Here are some of the most frequently asked questions about the selection and use of electric linear actuators.

电动线性执行器与直流电机相同吗？

Is an Electric Linear Actuator the same as a DC motor?

电动线性执行器与直流电机不同。直流电机利用电磁场将直流 (DC) 电能转换为电机轴上的扭矩。扭矩的大小和方向与电流的大小和方向成正比。

电动线性执行器包含一个直流电机。它将电机的扭矩转换为活塞的线性运动，活塞的伸展或收缩由电机的旋转方向决定，而活塞的动态力则由电机扭矩和齿轮系扭矩比决定。

An electric linear actuator is not the same as a DC motor. A DC motor uses electro-magnetic fields to convert direct current (DC) electrical energy into torque at the motor shaft. The magnitude and direction of the torque are proportional to the magnitude and direction of the electrical current.

An electric linear actuator contains a DC electric motor. It converts the motor’s torque into the linear motion of a piston with piston extension or retraction determined by the direction of the motor rotation and the piston’s dynamic force determined by the amount of motor torque and gear train torque ratio.

可以在项目中使用电动线性推杆吗？

Can I use an electric linear actuator for my project?

当然可以。电动线性推杆比气动或液压推杆设置更简单、更快捷。它们非常适合需要长寿命和低维护成本的项目，例如推、拉或提升面板、横梁、通风口、杠杆、夹持器和关节等物体。

Absolutely. Electric linear actuators are much simpler and faster to set up than pneumatic or hydraulic actuators. They are excellent for projects requiring extended life and low maintenance pushing, pulling, or lifting objects such as panels, beams, vents, levers, grippers, and joints.

如何同步两个或多个线性执行器？

How do I Synchronize two or more linear Actuators?

线性执行器活塞的速度取决于多种因素，例如附着质量、连杆的可变方向、动摩擦力、重力以及输送至直流电机的功率。因此，即使两个线性执行器接收相同的电压，它们也几乎肯定会根据所连接的负载以不同的速度运行。

同步运动控制需要一个控制回路来处理来自线性执行器的位置反馈，并自动调整驱动功率以实现一致的运动轨迹。两个或多个在位置反馈控制下运行且轨迹匹配的线性执行器将同步运行，无论负载如何变化。

“ACT-U8 DC-112 运动控制器”是一款坚固耐用、易于使用的电动线性执行器控制器，可提供高速位置反馈控制、线性执行器校准和自动实时轨迹生成。

The speed of a linear actuator piston depends on factors such as the attached mass, the variable orientation of linkages, dynamic friction, the force of gravity, and the power delivered to the DC motor. Thus, even if two linear actuators receive the same voltage, they will almost certainly run at different speeds in response to their connected load.

Synchronous motion control requires a control loop that processes position feedback from your linear actuator and automatically varies the drive power to achieve a consistent motion trajectory. Two or more linear actuators operating under position feedback control with matching trajectories will run synchronized regardless of variations in the load.

The “ACT-U8 DC-112 Motion Controller” is a robust, easy-to-use electric linear actuator control that provides high-speed position feedback control, linear actuator calibration, and automated real-time trajectory generation.

In What Direction Can I Apply Loads to a Linear Actuator?

可以在哪个方向对线性执行器施加负载？

当活塞伸缩时，沿活塞轴线施加力时，电动线性执行器性能最佳。它们在推动或拉动连接在活塞和主体紧固件之间的负载时同样有效。

设计人员应使用安装U形夹和销钉来安装线性执行器，并使负载和执行器以低摩擦旋转。低摩擦旋转至关重要，例如，当线性执行器打开绕其铰链旋转的面板时。线性执行器、面板和底座之间的角度会随着面板的打开而变化。

大多数线性执行器无法承受施加在活塞轴线外的力。这些力也称为侧向载荷，会使活塞悬臂靠在外筒上。例如，侧向载荷会导致活塞和气缸接口过早磨损，并降低防止碎屑侵入所需的密封性能。侧向载荷还可能导致活塞、丝杠和驱动螺母变形或磨损。在设计系统时，请确保线性执行器由外部结构、接头或导轨支撑，以免受到侧载。

Electric linear actuators perform best when forces are applied along the axis of the piston as the piston extends or retracts. They are equally efficient at pushing or pulling loads attached between the piston and body fasteners.

Designers should use mounting clevises and pins to mount linear actuators and allow the load and actuator to rotate with low friction. Low friction rotation is essential, for instance, when a linear actuator opens a panel that rotates about its hinge. The angles between the linear actuator, panel, and base will change as the panel opens.

Most linear actuators do not support forces applied off-axis of the piston. Also known as side-loading, these forces will cantilever the piston against the outer cylinder. Side loading can lead, for instance, to premature wear of the piston and cylinder interface and degrade any seal required for debris intrusion prevention. It may also deform or wear the piston, lead screw, and drive nut. When designing your system, ensure the linear actuator is supported by an external structure,  joint, or rail so that it is not side-loaded.

线性执行器有不同的速度吗？

Are Linear Actuators Available in Different Speeds?

电动线性执行器的速度范围很广，从每秒不到一英寸到每秒十英寸或更高。线性执行器的最大速度取决于内部直流电机的最高转速和齿轮系比。根据齿轮传动定律，电动线性执行器的速度和扭矩（或动态力）是相互制约的。对于给定的直流电机型号，速度越快，执行器提供的最大动态力就越小。另一方面，大推力执行器的最高速度会较低。此外，任何电动线性执行器的速度都会随着活塞上的负载而变化。制造商应该提供速度与推力的关系图，以便查找计划负载下的最大速度。

Electric linear actuators are available at a wide range of speeds from less than an inch per second to 10 inches or more per second. The maximum speed of a linear actuator is a function of the internal DC motor’s top speed and the gear train ratio. Due to the law of gears, an electric linear actuator’s speed and torque (or dynamic force) are a trade. For a given DC motor model, faster actuators offer lower maximum dynamic force. On the other hand, high-force actuators will run at a slower top speed. Also, the speed of any electric linear actuator will vary with the load present at the piston. Manufacturers should provide a graph of speed versus force to allow you to look up the maximum speed under your planned load.

电动线性推杆的常见故障有哪些？

What are the common failures of Electric Linear Actuators?

电动线性推杆是一种用途极为广泛的工具，适用于各种行业和应用。在设计和制作原型以了解线性推杆的极限时，请注意以下常见故障模式。

过电流会损坏直流电机，并导致电刷、换向器或电枢绕组开路或短路。过电流最常见的原因之一是电机失速后未能移除驱动电压。电机可能在达到活塞行程或负载超过最大动态力时失速。

电动线性推杆过热会损坏电机和齿轮系。当运行频率超过其额定占空比或在高环境温度下高负载运行时，推杆最常发生过热。

Electric linear actuators are incredibly versatile tools suitable for various industries and applications. As you design and prototype to learn the limits of linear actuators, be aware of these common failure modes.

Over-current will damage DC electric motors and cause an open or short circuit of brushes, commutator, or armature windings. One of the most common causes of overcurrent is the failure to remove the drive voltage after the motor stalls. It may stall upon reaching the extent of the piston or under a load that exceeds the maximum dynamic force.

Overheating an electric linear actuator will damage the electric motor and the gear train. Actuators most commonly overheat when running at a frequency exceeding their rated duty cycle or operating under high load at elevated environmental temperatures.

线性执行器有哪四种类型？

What are the 4 types of linear actuators?

线性执行器主要有四种类型。电动线性执行器使用电动机产生运动，这使其成为精确控制和节能的理想选择。液压线性执行器利用流体压力产生力，以紧凑的形式提供高功率。气动线性执行器依靠压缩空气产生运动，以其高速和清洁的运行而闻名。最后，机械线性执行器采用机械机构，例如丝杠或齿轮，通过手动曲柄或轮子提供简单可靠的运动。

There are four main types of linear actuators. Electric linear actuators use electric motors to produce motion, which makes them ideal for precise control and energy efficiency. Hydraulic linear actuators use fluid pressure to generate force, offering high power in a compact form. Pneumatic linear actuators rely on compressed air to create movement and are known for their high speed and clean operation. Lastly, mechanical linear actuators employ mechanical mechanisms, such as screws or gears, providing a simple and reliable motion through manual hand cranks or wheels.

线性执行器有哪些优势？

What are the advantages of linear actuators?

线性执行器具有诸多优势。它们能够精确控制运动和位置，这对于需要高精度的应用至关重要。其简洁的设计确保了可靠性和易于维护。此外，线性执行器比其他运动系统更节能，因为它们无需任何额外机构即可直接将能量转换为线性运动。线性执行器还提供电动、液压和气动等多种类型，从而能够灵活地应用于从工业机械到机器人等各种应用，并可根据特定的功率、速度或环境需求进行定制。

Linear actuators offer several advantages. They provide precise control of movement and position, which is essential for applications requiring high accuracy. Their straightforward design ensures reliability and ease of maintenance. Additionally, linear actuators can be more energy-efficient than other motion systems, as they directly convert energy into linear motion without additional mechanisms. They also come in various types, like electric, hydraulic, and pneumatic, allowing for flexibility in different applications, from industrial machinery to robotics, tailored to specific power, speed, or environmental needs.

如何选择电动线性推杆？

How do I choose an electric linear actuator?

选择电动线性推杆时，务必考虑几个关键因素，以确保其满足应用的特定要求。首先，通过评估负载能力来确定推杆必须施加的最大力。选择能够承受负载且不超过其承载能力的推杆至关重要。其次，考虑所需的运动速度，因为推杆具有各种齿轮比，这些齿轮比决定了其伸缩速度。行程长度是另一个重要方面，因为推杆伸出的距离应与应用的运动范围需求相匹配。

考虑线性执行器的工作环境也至关重要。评估占空比，即执行器在不过热或磨损的情况下可以运行的频率。温度、湿度和潜在的污染物暴露等环境因素也会影响执行器的选择，并影响其是否配备适当的保护措施。确保执行器的电压和电流要求与可用电源相匹配至关重要。最后，如果应用需要精确控制或位置反馈，请考虑其他功能，例如内置限位开关或反馈传感器。

When selecting an electric linear actuator, it is crucial to consider a few key factors to make sure it meets your application’s specific requirements. First, determine the maximum force the actuator must exert by assessing the load capacity. Choosing an actuator that can handle the load without exceeding its capacity is essential. Next, consider the required movement speed, as actuators come in various gear ratios that determine the extension and retraction rates. Stroke length is another crucial aspect, as the distance the actuator extends should match your application’s range of motion needs.

It is also essential to consider the operating environment of the linear actuator. Evaluate the duty cycle, which refers to how often the actuator can operate without overheating or wearing out. Environmental factors, such as temperature, moisture, and potential exposure to contaminants, also play a role in selecting an actuator with the proper protection measures. Ensuring that the actuator’s voltage and current requirements align with your available power supply is crucial. Finally, consider additional features, such as built-in limit switches or feedback sensors, if your application requires precise control or positional feedback.

Conclusion

结论

电动线性推杆是设计师为各种行业和应用提供运动解决方案的绝佳工具。它们部署快捷、操作清洁，并且几乎无需维护，使用寿命长。将线性推杆与功能强大的运动控制器（例如 ACT-U8 DC-112）相结合，将为高级运动规划和实时控制带来无限可能。

Electric linear actuators are an exciting tool for designers to deliver motion solutions across diverse industries and applications. They are quick to deploy, clean to operate, and require little maintenance to achieve long operating life. Combine your next linear actuator with a capable motion controller such as the ACT-U8 DC-112 to open up great opportunities for advanced motion planning and real-time control.