Tiny valve

[mrn]

Hello, I was wondering if anybody could help me design a valve that is about a 1/2 inch by 1/2 inch. I need it to be controlled by a tiny electromagnet, or something that can be controlled by electricity.

I have one design, however I am having trouble with leakage, that is why i'm looking for a better design.

 

[panic mode]

what is the valve for? compressed air? water?
what is the pressure differential?
why don't you use any of many ready made valves?
what dimensions are 1/2"x1/2/"? footprint?
how about height? is it restricted?
where is the flow? through the black ziz-zag thing that may represent a pipe?

 

[mrn]

its basically water the same consistency
I don't use ready made valves, because none are that small

.5"x.5" width/length by 1.5" tall

the height its not as big of a deal, but smaller the better

yest the black line is the pipe/tube or whatever.

 

[panic mode]

ball valves are simple and reliable but would probably be hard to make in that size.
the point is to make a seal with round feature where hard piece rests on soft seat and water pressure itself ensures tight fit and no leak...
using pin with hole (or two) should do the job and allow actuation by solenoid. the devil is in the detail but this is quite similar to what you have.

another idea is to try to make or modify checkvalve (by drilling small hole for actuator shaft) and add solenoid to force the valve open (of course this only works one way). without solenoid active, checkvalve would close and maintain good seal. new made hole would need to be a tight fit for the actuator pin. it would only be exposed to water pressure when solenoid is active and ball is pushed out of closed position (valve open). but even then the lowest pressure is toward output port so leak (if present) would be minor and only when valve is open. it could be also sealed completely by adding bellow. if you like you could make everything yourself.

but i'm just an EE guy, not a fluid dynamics specialist and i can't take any blame. after all i am not sure of your handyman skills.

 

[atferrari]

Some years ago I had the chance to see hardware used by surgeons.

Valves, connectors and plugs were diminute. Impressive.

I have no idea how easy is to get some, much less where.

 

[mrn]

@panic: that could work the only problem is making a solenoid that small, would be pretty difficultm, i'm assuming anyways. Do you have a referance image for the check valve your talking about?


I found this valve they use for dispensing medical fluids for like testing and what not, in a sense I guess it is a simple solenoid.

https://www.fgyger.ch/index.php?article_id=53&clang=1

 

[panic mode]

i like it, it's completely sealed and looks awesome.
it also uses checkvalve to block the flow...

 

[KMoffett]

You might have a look at miniature Lee Valves: https://www.theleeco.com/efsweb2.nsf/Products!OpenPage

Ken

 

[House0Fwax]

Just as a suggestion, have a look at the solenoid valves used in PIR air fresheners. I have one here and it measures roughly 15mm X 15mm x 20mm.

 

[mrn]

@KMoffet: I actually was looking at these this morning.


@HouseOFwax: that is a good idea! however I know there motion activated, how could I use this in my project? maybe a tiny solenoid that passes in front of the pir sensor?

 

[House0Fwax]

Actually, I meant get hold of a PIR air-freshener, tear it apart and have a look at the solenoid valve itself.
I have one on the bench that I'm not sure what I'll do with it. As I said, just a suggestion.

 

[KMoffett]

Actually, I meant get hold of a PIR air-freshener, tear it apart and have a look at the solenoid valve itself.
I have one on the bench that I'm not sure what I'll do with it. As I said, just a suggestion.

Out of curiosity, can you post a photo of the valve?

Ken

 

[House0Fwax]

can you post a photo of the valve?

Certainly.

 

[KMoffett]

Is this actually a valve with input and output ports, or just a solenoid that pushes on a valve of the scent container, like the stem on the top of a spray paint can?

Ken

 

[House0Fwax]

This item sits on top of a pressured 'refill' and when energised allows the air-freshening stuff to flow through.
The refill sits in the end with the rubber seal (Pic 3) and the air-freshening stuff squirts out of that tiny hole on the opposite end (Pic 4).

:Edit:

Here is a link for the PIR bit of the unit I took apart, unfortunately, it doesn't show the solenoid.
https://www.instructables.com/id/Re-purposing-an-Air-Wick-Freshmatic-Compact-i-Moti/?ALLSTEPS

Note the 'Step 1: Avoid the Competition' where it describes a gearbox variety.

 

[mrn]

So i'm thinking maybe a electromagnet valve would not work so well, I am having trouble getting a good seal, because the ball is so tiny it doesn't have enough weight to help seal off the hole. I'm thinking now more of a bubble jet printer type valve, someone has mentioned this before and I didn't really think about it that much.

if you don't know how bubble jets work just Google them, there pretty cool.
anyways my question is how would I heat the liquid up that fast and that rapidly(2-3 times per second)?

My first thought would to use nichrome wire like they use for heating elements for toasters and such, however can nichrome wire heat up that fast?

also I don't have any so a different heating approach would be better so I can try it out.

 

[panic mode]

check valves have a very good seal and they are easily made even using basic tools. all you have is funnel shaped hole in a material and a ball. if the flow is in the right direction, ball jams and creates seal. in practice, you don't rely just on gravity and flow to jam the ball and create seal, there is a spring to help it out so valve can operate in any orientation and even if there is some vibration. leak can occur if pressure differential is too low or spring has failed or if the hole is not round. are you sure you are using it the correct way? if you reverse ports, pressure may overcome spring and you get flow all the time. roundness of the hole is easily achieved by using spinning cutters such as drill bit for example (well, that is the hands of a skilled person, others can manage produce all kind of non-desired but funny results like drill right throguh, make a triangular hole, etc.). an example of silly mistake that will make non-round and therefore leaky funnel is drilling by hand (without bench press), drilling too fast (drill didn't have time to even out the funnel) or worse - stop drilling while bit is still in material (leaves . depending on shape of the drill you can get shallower or deeper funnel. the medical valve mentioned earlier works just like that - ball is attached to a rod (iron core). when coil produces magnetic field it pulls the rod which also puls the ball out of the funnel and valve is open. when coil is deenergized, spring action (helped by liquid pressure) moves ball back into the funnel and creates seal. devices operated by solenoids (relays, solenoid valves etc.) have response time on the order of 10-15ms so getting valve to open and close 3 times per second should not be a problem.

making own bubble jet is going to be a problem because those things operate of very different (miniature) scale. this is why they can heat up and cool down fast - they are microscopic. also the flow rate you get is minute. you would have more luck using piezo elements, they can operate fast, can be small etc.

 

[mrn]

@panic mode: is there a possibility of doing a check valve without the spring? Otherwise that adds extra force that the coil needs to pull, and in this case i'm trying to get that as little as possible. the problem with the check valve is it requires a strong coil, witch takes quite a bit of wire, and long long hours of winding coils. So I was trying to find a "solid state" valve of some sort. however a check valve would be much simpler.


Right, however I thinking of just taking the concept and scaling it up a bit, but would require more heat or a bigger crystal and more power.

 

[panic mode]

sure, just mount it vertically (or any suitable angle so that ball rolls down the funnel due gravity).

 

[throbscottle]

You should try taking apart a liquid hand soap dispenser valve to see how they work - they have a little ball and spring in them (actually a good source of small springs if you need them). Maybe some ideas there?