Solenoids: Push and Pull??

[qs101]

Hi there, I'm new to this forum but I just wanted to know if anyone has heard of a solenoid (actuator) that is possible of being both push and pull, rather than the conventional push or pull. It says that it isn't possible to have such a thing on http://www.societyofrobots.com/actuators_solenoids.shtml   , but was just wondering that if there was such a device, would it be of any use? because I've come up something that does both push and pull, and it doesn't use/contain springs, just magnets.

Thanks

[Robotboy86]

The thing that you are talking about is a linear acuator..
http://en.wikipedia.org/wiki/Linear_actuator

It is different then a solenoid in that a linear acuator can move both ways.  A solenoid moves one way, with a spring.. and very rapidly at that. 

Infact, the wikipedia article on solenoids actually refrences "http://www.societyofrobots.com/actuators_solenoids.shtml"  US! YAY!

[Rebelgium]

And qs101 ? Is your invention better? 

[ed1380]

I'm guessing its 2 selinoids in one. with a centering spring.

[qs101]

Ok first of all, I know what a linear actuator is, I went to that site as well, however if you look at the diagram, the sliding tube does move both in and out, but mine differs in that you have a solenoid, and the plunger enters one end, and exits the other. So instead of a plunger getting stuck in the middle because of the = but opposite forces, my plunger is able to pass right through.
  Whether or not my invention is better really depends on how useful it is to society and its market value. So far the ideas that I've come with are good, but they need alot more work.
  And finally no, it ain't two solenoids, just the one, and there are no springs. Another thing that makes it unique is that if you compare it to normal solenoid locks, which require power to either stay locked or open, my design doesn't. So if you lock it, then you only use power to initiate the lock, not to keep the lock locked, likewise when its open.

Hope that makes things a bit clearer.

[Ro-Bot-X]

Check out the linear actuators on the Trossen Robotics website.
http://www.trossenrobotics.com/linear-actuators.aspx

[Robotboy86]

So you made a solenoid that is springless, and go back and forth?

Can we get some specs?  What kind of force/torque is it putting out?  With what voltage/amperage?

Also, are you *sure* its not just a linear actuator that moves very fast? 

[paulstreats]

does it use a solid magnet as the plunger? it would be possible to do it this way

[qs101]

I haven't got any firm specs on it yet, the model that i got built was only designed to test my theory, all I know is that it can work/move in the horizontal plane of 3V, and about 12V in the vertical plane. The plunger is a special design and it uses rare earth magnets. The solenoid 30m of winding, so the actual solenoid isn't very powerful, im pretty sure that if I had more windings, shrunk the design down, it should run at less than 1V. In terms of torque, I haven't figure that out yet (I'm a 2nd yr Science student with majors in Biochm & Developemental Biology, only did Physics 101!!), so I'm waiting for my mech. eng. friend to figure it out.
   Trossen Robotics has actuators. that isn't what I have, actuators have motors & gears, mine doesn't. So no it ain't an actuator that moves really fast, it's something else that can move really fast.
In terms of ideas, so far I've thought of: next gen solenoid lock, car engine, e-gun.

[ed1380]

pics or it didnt happen

[paulstreats]

im pretty sure that it could be made with a regular magnet althoug the power would decrease over time.
I should imagine that if you add more turns on the coil, it would allow more torque but only because it would allow more voltage.
It might be worh looking at trying to make the same thing but with an electromagnet in the centre as well, an initial design would probably use brushes like motors do, but if you could use ball bearings to centre the plunger, you could send the electricity through them.

[qs101]

Its pretty pointless posting up pics because you can't actually see it work. Even if I made a video, you still couldn't see very well, you need to see it for real. In terms of putting an electromagnet inside, it would be good in theory, but it wouldnt be practical unless u required high amounts or torque.
  Besides that, I still haven't seen any posts in regard to its use! Which is kinda the 1st question to this topic.

[paulstreats]

you can alter the toque by altering the voltage. The advantage would be that the electromagnet wouldnt weaken over time.

It has many practical uses, such as joints, replacing linear actuators for some applications, driving pneumatics systems. Even none robotic ones like electric door locks etc...

I'm sure that if you could bring a product like that to the market at a reasonable price, they would sell fast enough

[qs101]

OK, so my invention does have some uses. I'll try and see if modify the plunger to use electromagnets rather than the rare earth magnets. Btw, what's reasonably priced? I from Australia and well they don't really have many robotics shops around, even at uni. Thanks for the ideas, I'll keep you guys posted if anything interesting turns up.