Help needed - opening the water flow

[Rob2008]

Hi guys,


I'm new to engineering, yet I have to design a metal mechanism that lets
though a flow of slightly pressurized liquid when a button is press
down.





Currently I came up with something like that.

When the button is unpressed, its part is blocking the way of the
liquid, but when it is pressed, a hole in it lines up with the canal
and the liquid goes through.



Yes I'm afraid that in reality there would be a gap and the liquid would be leaking all the time.



What would you suggest? Maybe there is a more effective solution? Or
maybe if using some special materials the leaking would not occur?




Thanks!

 

[vlad1979]

I don't know what application is this for. But I don't think it's worth the trouble to design such think. There are plenty of valves and faucets on the market that does this job.


http://en.wikipedia.org/wiki/Categorylumbing_valves


But if this is some sort of a "school"assignement I suggest you take a look at the valves and faucets design and adapt that to your application.

 

[Rob2008]

Hi,

Thanks for the tip! Well, it isn't really a "school project". I am a
concept artist and we received an order to model a specific object (
unfortunately I can't disclose what it really is ). I made the concept
drawing and we have people who are now making the outer shape in
SolidWorks, but we don't have an engineer in out team, so making this
inner mechanism is kinda tricky.



Using a pre-made mechanism would be a great solution. Yet as the canal
itself is about 1.5 mm in diameter and the whole device should be about
10 mm , I wasn't able to find a valve mechanism that small.



Maybe someone know where to look for it?



And meanwhile we came up with something like that.

Looks fair simple and, hopefully, with the right kind of plastic and washers won't leak. What do you think?

 

[Rob2008]

And the same concept in 3d, what do you think?

 

[vlad1979]

OK this are my thoughts on the subject. I don't know much about faucets (tap) (don't know exactly how are they called) only the ones I disassembled at home

but to me those o'rings like you have them now they will wear against those sharp edges when they move.


As I know they usually don't work like yours, but rather like the one in this picture it has a sphere with a hole in it (the yellow one) and when it rotates to one side the hole is blocked by the walls and when it rotates to the other side it lets the fluid to pass thru:


http://laparrej.free.fr/Images/sw/robinet_eclate.gif


So adapting that to your situation could be something like below:


View attachment 3822


Make the main pin larger then 1.5mm so when it rotates the hole in it gets all blocked by the walls. But you will need some sort of locking mechanism for the pin to not move horizontal to allow it only to rotate. You could even get a sphere in there look at a faucet to see how it works, take one apart. Now I'm giving you destructive advices

I know this is kind of another design then yours but hey a little "brainstorming" doesn't hurt.

Some links maybe they will help you with ideas:


[url]http://static.howstuffworks.com/gif/how-to-stop-faucet-drips -1.jpg[/url]


http://www.rd.com/familyhandyman/content/17548/


[url]http://www.remodelguide.com/improve/plumbing/faucets/faucets _works.html[/url]


http://www.indepthinfo.com/gadgets/faucet.shtml


http://wilwaylumber.com/howto/plumbing/howto011.htm

 

[Rob2008]

Privet, Vlad!

In that 3d concept there were no o-rings used, as I thought if using
the right kind of plastic, one could go without them... yet you gave me
an idea!

Since using the big, red turning hands would still be kida unlikely from the design point of view, we could make it that way.

Pressing the button would result in turning the pivoting handle, so
opening the flow and releasing the button would let a spring turn back
and close the flow again.



A bit harder to make, from the engineering point of view, yet much more secure from leaking.

 

[vlad1979]

Actually those red lines I draw means to delete that lever, the spring and have just the main pin, the oring's with some o'ringgrooves in the main pin for the o'rings to sit in and with a privet on that side to rotate it.


Your last design will be difficult to achive if not impossible, and now I'm referring to the sphere, there's no way to get it inside like you draw it. And that grey lever in the last picture it will not rotate like you draw it.

 

[Rob2008]

Unfortunately the original outer design won't allow us remove the button and replace it with that rotating thing.

But thanks anyway! Now we have found an engineer who would be able to construct it.

 

[verge]

Just caught this thread. What you're looking for is probably a ball valve-type design. I see what you're saying about the size, though. Wow, that's tiny. Interesting assignment! Sounds like a fun job you have.


You might have to use something like a powder metal process to make something that small. Of course, I know a little about that, whereas I'm not up onhow some of this really miniature stuff is made nowadays. I'd love to hear how this is finally solved...

 

[mcgowanp]

Hey Rob, for the size that you are talking about I would recommend that you develope your second idea. I've just finished a project dealing controlling water flow. Except that instead of using a spring use a diaphram spring, its a convexed plastic part that will deflect and return to normal when the force is lifted. Your cyclinder with the flow hole in it should be contained in a more mechanical manner but I'm sure that your not showing us all the details in these sketches. You defo need to seal up around the water volume with at least one O'Ring on each side, 2 if you can manage it. www.parker.com give some good guide lines on the gland required for O'rings - remember that your system will be semi dynamic, in that at one point (with the valve closed) the water will not be flowing and the water pressuer will be at its max. Then when the valve is opened your pressure will drop as water passes through. THis means that your O'rings will be under varying pressure during normal operation. Since you cant give us details on the outside of the part, if you have you cyclinder mechanically contained then it may allow you to stream line the interface portion of this device - make it look more fancy!!.


Your second Idea is a fairly standard approach to this kind of problem. So your on the right track, I would take a bit more time to develope it a little bit further from an engineering point of view.


By the way, looking at previous comments your O'rings should be contained in your static housing and should never be exposed beyond the travel of the cyclinder.


Check out Clippard as they do minature valves, also bosch rexroth web site have some very nice solutions.


Keep at it you'll get there.


Paddy
Edited by: mcgowanp

 

[Rob2008]

Hi guys,

After having the prototype printed out in 3d i realized that it is so
small that any kind of plungers, faucets and other valves are
completely out of the question.

And came up with this solution - the red one is a tiny rubber tube and
the blue one is a spring that pinches the tube. When the spring is
pressed down ( the green arrow ), the tube is released and the liquid
can flow. Nice and easy.