Inner working of a linear actuator

In summary, the working mechanism of the actuator involves applying current to the solenoid, which induces magnetic fields according to Ampere's Law. These fields are strengthened and confined within the actuator due to the high permeability of the plunger. The force that moves the plunger horizontally is a result of the spatial derivative of the energy, and in the absence of friction, the plunger will oscillate. The energy required to maintain the magnetic field is proportional to the permeability and the square of the magnetic field strength. Dissipation, which is caused by the Joule effect, is necessary to maintain the plunger's movement and also to create the external magnetic field. However, it is not necessary to consider dissipation in understanding
  • #1
geft
148
0
I need to describe the working mechanism for the following actuator.

gswl6.png


Here's what I've written so far:
Current is applied to the solenoid in order to induce magnetic fields within the actuator in accordance to Ampere’s Law. Since the plunger has high permeability, the magnetic fields produced would be strengthened and confined to the actuator. The fields produce a force which in turn moves the plunger horizontally.

However, I feel that I'm missing something. In particular, how is the force that moves the plunger generated? Is it really due to the magnetic fields? I know of the right hand rule where force points away in the direction of the palm but according to that rule, the force should actually point in the direction perpendicular to the supposed plunger movement. Is it driven by the mmf?
 
Physics news on Phys.org
  • #2
The simplest way to consider it is through energy: the more "plunger" you have inside the coil, the lower the energy. Force is just the spatial derivative of the energy, so it enters. In fact, in absence of friction, it will just come out the other side and oscillate.

An "Ampere law" version is more complicated, seriously.
 
  • #3
But where does that energy come from? Since this actuator is driven by current, how does the total electrical energy change with respect to the size of the plunger inside?
 
  • #4
When putting current through the coil, you need some energy to fight dissipation, and also some energy to create the external magnetic field. The energy of the magnetic field is proportional to the permeability times B^2, integrated to all the volume. When you put the plunger inside the coil, the magnetic field is cheaper to maintain.
 
  • #5
I see, but why do we need energy to fight dissipation? I thought dissipation is due to energy?
 
  • #6
Don't worry about dissipation to understand this, even if it is not present, the plunger will feel the force inwards.

In any case, dissipation is due to Joule effect: dissipated power = intensity times voltage drop...
 

1. What is a linear actuator?

A linear actuator is a device that converts rotational motion into linear motion. It is commonly used in many industrial, commercial, and consumer applications to move or control objects in a straight line.

2. How does a linear actuator work?

A linear actuator typically consists of a motor, gears, and a lead screw or ball screw. The motor rotates the gears, which in turn rotate the lead screw or ball screw. This rotation of the screw causes a linear motion to occur, pushing or pulling the actuator's rod in or out.

3. What types of linear actuators are there?

There are several types of linear actuators, including electric, pneumatic, hydraulic, and mechanical. Electric linear actuators use an electric motor to drive the motion, while pneumatic and hydraulic actuators use air or fluid pressure. Mechanical linear actuators use a manual crank or lever to generate the motion.

4. What are the applications of linear actuators?

Linear actuators are used in a wide range of applications, such as robotics, manufacturing, medical devices, and automation. They can also be found in everyday items like electric windows, doors, and recliners.

5. How do I choose the right linear actuator for my project?

The type of linear actuator you choose will depend on the specific requirements of your project, such as the required force, speed, and precision. It's important to consider factors like load capacity, stroke length, and power source when selecting a linear actuator. Consulting with a specialist or doing thorough research can help you determine the best option for your project.

Similar threads

Replies
18
Views
842
  • Electrical Engineering
Replies
7
Views
781
Replies
11
Views
1K
Replies
9
Views
2K
  • Mechanical Engineering
Replies
2
Views
1K
  • Mechanical Engineering
Replies
3
Views
3K
  • Other Physics Topics
Replies
3
Views
2K
Replies
1
Views
4K
Replies
1
Views
3K
  • Electromagnetism
Replies
2
Views
801
Back
Top