Hello everyone! I’m trying to figure out what the small magnetic pins would do inside of a Koganei HEA series solenoid. It seems that these demagnetize over time and cause older solenoids to exhibit issues when undergoing high-frequency cycling. If I’m understanding the operation correctly, these pins simply act to transfer force from the armature up to the piston that activates the pilot valve - so why would they need to be magnetized?
Here’s a link to the Koganei site:
And a (unfortunately unlabeled) diagram of the solenoid:
If anyone could assist with locating documentation that would explain these small magnetic pins, that would be helpful as well. I’ve looked for the patent, but can’t locate it.
Since the solenoids are about $80 each, I’d like to be able to refresh my old ones instead of simply purchasing new. Any help would be much appreciated.
Update… Somehow I used the right keywords and found the patent. Assistance in understanding would be appreciated as well. The part I’m describing appears to be part number 46.
I’m not seeing anything magnetic in that patent connected to the interlock pins, or really anything obvious as to why they would be magnetic.
If you are opening your valves and looking at these pins, there is a VERY high chance they will not work afterwards… Stuff like this is really not dirt tolerant!
My guess here would be that magnetizing add hysteresis to the valve (position holding) or prevents something from rattling around when its shaken.
Maybe the opposite. They magnetize over time interfering with the operation?
Other possibilities. The pilot section has gotten dirty and blocked up. The o-rings have hardened not allowing the valve to shift… The o-rings are leaking.
I have purchased some of these new from the manufacturer within the last year, and the interlock pins are certainly magnetized new, and lose it over time. Swapping the interlock pins seems to give new life to an old solenoid (dwell time for a cycle reduced significantly). Swapping the spools didn’t seem to make a difference.
After reading through the patent last night, I came to a similar conclusion that the magnetization is somewhat irrelevant. However, on a solenoid that has been cycled hundreds of thousands of times, it’s likely that the conical springs are worn out. But on the downswing of the armature of the solenoid, if those interlock pins are still strongly magnetized, they assist in closing the flapper valve by an attraction to the spring behind the flapper. As the interlock pins lose magnetization, they no longer assist in this action, and the flapper valve relies only on a tired, old conical spring to close it.
That’s the only way that I could reason that swapping the interlock pins between a new solenoid and an old solenoid seems to give it some new life - but my guess is replacing the springs would have a far greater impact.
Regarding the demagnetization; anyone have tips for magnetizing some very tiny parts?
Stick them onto a strong neo magnet in the right orientation (standing up, correct N/S)? Pull straight off, put them back, repeat a few times. That’s about all I can offer
