Searching for a special electromagnet

[Ghandi123]

Hello guys,

I am searching for a special Electromagnet (reasonable priced) for my project. I want to replace a permanent magnet which opens a valve by attracting a stainless steel cylinder (with a small magnet inside to better attract) if the magnet is moved into position by pressing a button. Instead I wanted to install an electromagnet which operates via an Arduino. But it would be best if I don't need to open the valve-body so i don't compromise the sealing and functionality.
I measured the holding force of the permanent magnet to approximately 12N. The maximum force needed to compress the spring is ca. 2,5N.

Below i have a rough sketch of how it (should) look like and how i want it to function.

I have already tried some things i had at home/where easy to get:
1) a replacement-magnet for a solenoid valve like seen here: Solenoid-Valve
Problem: the point where the magnetic force is strongest i too far from the cylinder to attract it.
2) a holding magnet in which i drilled a hole: holding-magnet
Problem: the magnetic field is really shallow and can not attract the cylinder. Plus in the middle, the magnetic force is the lowest and by drilling it i lowered it more.

My further ideas where to get a magnet with a lower height so the point of the maximum magnetic force is closer to the cylinder. But I struggle to find one of those and I am not sure it will even work with it.

If anyone of you could help me with this i would be very thankful.

Thanks

 

[ClydeCrashKop]

Can you use a solenoid to push the original equipment button?
Maybe with a cam or lever for mechanical advantage.

 

[rjenkinsgb]

Try the solenoid coil again, but add an iron slug in the spare space beyond the stainless steel part? That should significantly increase the force.

 

[Ghandi123]

Can you use a solenoid to push the original equipment button?
Maybe with a cam or lever for mechanical advantage.

Yea that could work but i tried to stay in the original casing. Those are my backup-plans. They should work either way but the solenoid would make it rather big and maybe too bulky. Since i wanted to just replace the manual button with a fixed (3d-printed) cover roughly the same size.
The metal slug seems to be a good alternative, but if I can manage it without opening the water chamber I would be really glad, since I do not want to compromise the functionality of the valve.

 

[Tony Stewart]

There are many ways to move an object. Consider that the coil field and permanent magnet fields must overlap over the whole range of travel to couple the flux in the ferrous material. Consider how a speaker coil is tightly fit between magnets.

Wikiwand - Solenoid

A solenoid is a type of electromagnet formed by a helical coil of wire whose length is substantially greater than its diameter, The helical coil of a solenoid does not necessarily need to revolve around a straight-line axis; for example, William Sturgeon's electromagnet of 1824 consisted of a...

www.wikiwand.com

 

[Externet]

Appliances use 'not special' solenoids; like a in a dishwasher, in a 'clean' cycle range...

Abundant in discarded ones, like :
----> https://www.amazon.com/Supplying-De...t=&hvlocphy=9014335&hvtargid=pla-835494407279

Canibalize !