Spring Release Relief Mechanism

[krus1972]

I have a simple electric linear pull solinoid. The solinoid has a linear return spring on the plunger. The plunger has a "C" washer that is used as a spring stop so that the spring will compressed wheen the solinoid pulls it's distance.

I would like to replace the "C" washer with something that is able to expand when a small amount of voltage is put to it. The purpose is that sometimes I want the return spring to engae and sometimes I don't want the spring to engage when powering the solinoid. Of coarse, when the spring is not engaged the solinoid won't return.

My goal is that I want to control when the linear solinoid should return to it's original postion and when it shouldn't. Keeping the solinoid energized is not an option becauase power is not available.

I was thinking of some sort of mechanism to replace the "C" washer. It will expand so that the spring simply passes through instead of pushing up against.

Does anyone have any ideas if something like this is available?

Any ideas would be most appreciated.

 

[TheTick]

I'm certain I have seen solenoid valves that operate in a similar mannr.

 

[israelkk]

You are looking for latch solenoid.

 

[hydtools]

Something like this:

http://www.blpcomp.com/productinfo/solenoids4.php

Ted

 

[krus1972]

It can't be a latch solinoid because this would require the solinoid to have to overcome a force (spring). The goal here is that when the solinoid is activated, there would be little to no force the solinoid would have to overcome. The spring compression (or force) would be activated only if the plunger is MANULLY pushed. If the solinoid is activated ELECTRICALLY the force (spring) needs to be released.

The only way I can see how to do this is to have an electrically activated retainer of some sort that would allow the spring to pass through when activated electrially.

Any ideas?

Thanks for all of your ideas and help.

 

[MikeHalloran]

Well, yeah, but then you need another solenoid to do that, and according to you, 'power is not available'.

You need to refine your specification to better define exactly what you want, exactly what's available and when, and exactly what you don't want. A design should sort of fall out of that effort.

It might help to start with a state transition diagram. The device you want seems to have at least four states, and you need to define what's going on in each state, and what set of conditions causes a transition from each state to all other possible next states.



Mike Halloran
Pembroke Pines, FL, USA

 

[krus1972]

The pwer is available to activate the solinoid. There isn't enough to overcome the spring There is power to activate the solinoid if there is little or no retuirn spring force.

Something needs to be done with the retainer.

Any ideas?

 

[MintJulep]

Add a back-drivable acme thread to the shaft.

Your retainer is a nut with a groove on the outside.

Restrain the nut from rotating by engaging a pin in the groove and it will work as a spring retainer.

Allow the nut to rotate and the spring's linear force will spin it up the shaft.

 

[krus1972]

MintJulep,

That may work, but, getting the nut returned back to the original postion is an issue. I cannot place a spring on the opposite side.

I am thinking of a retainer of some sort that would expand when voltage is applied to it.

I don't know, maybe some more people here have ideas?