temporized mechanical block of button

[Davidenocita]

Good Morning to all!

I'm new on this forum, i'm a young italian materials engineer, and i'm glad to be part of this wonderful forum!

So, I'm on a little mechanical problem.....

Now I'm a bursar for the national research council of italy, and i have to make some studies for new materials and new mechanical systems.

I've got to design a system where when a button is pushed, it returns immediately in its start position and so cannot be pushed for a

certain number of minutes, after which the block is removed and they can push again the button.

The button has the function to squeeze a little reservoir of liquid, that after pressing the button, relase the liquid on a tube, and

after a few minutes refills entirely.

All the system has to be purely mechanical, so no electronic devices of any kind.

Thank you all and good morning!

Davide

 

[MintJulep]

If "a certain number of minutes" is the same as the time for the reservoir to refill then it could be a fairly straight-forward mechanical linkage and latch.

 

[MikeHalloran]

You might find the inspiration you need in the study of fuzes for munitions.
... of course you need the subset of fuzes that reset themselves.

Are electrical solutions excluded because of lack of local power, or because of some fire or explosion hazard? I ask because the act of pressing a mechanical button can be made to produce enough electrical power to run a modern microcontroller for a long time, so such parasitic power might be a viable option.



Mike Halloran
Pembroke Pines, FL, USA

 

[Jboggs]

You might consider a pneumatic control system. You can get pneumatic timers from several sources (Bimba, Clippard, SMC, Mead, and others).

Another suggestion: instead of locking the switch out (which can lead to a damaged switch) consider just disabling the switch during the delay. So even if someone pushed the switch nothing happens.

 

[Davidenocita]

Thank you for your answers!

First i'd want to understand better how the linkage and latch system can work for this problem.

Admitting that the time necessary for the reservoir to refill is equal to the time they need the button blocked(i will verify that),

do you mean something like the second image in this link?

http://www.daerospace.com/MechanicalSystems/DwellLinkage.php

If yes, how can the refilling of the reservoir (which is made of soft PVC) unlock the mechanism?

Then i would like to thank MikeHalloran for the tip on fuzes, i will made some culture on that.

So, any electrical solution for the moment is not usable for cost and safety reasons.

Davide

 

[Davidenocita]

Well! Even preumatic stuff could be useful! i will take a look on clippard.

Then, the fact is that the button itself is that which squeezes the soft reservoir

 

[DraftingMan]

Davidenocita,

You might look at float valves, similar to a toilet float valve, with a linkage to block the button when the reservoir is not filled.

https://www.google.com/search?hl=en...0.0....0...1ac.1.37.img..0.11.479.7PIdPlnp6UA

John H. Dunten, CD
Certified Drafter

 

[Davidenocita]

Thank you Draftingman, i will consider even this method!