How to stop oil going into a motor from the attached pump? Answered
I am fighting a little war with some oil pumps.
Attached to a 1/2HP motor the construction is quite simple.
To prevent leaking there is a spring loaded oil seal between pump and motor.
But this seal is never 100% if you deal with 180°C hot vegetable oil....
At these temps the stuff is literally thinner than water and sooner or later finds a way out.
Main problem I am facing is the drying of the vegetable oil.
Over time it turns intoa really hard resin.
But before that it manages to creep all the way into the motor bearing in the front part of the motor.
It drives out the grease and slowly replaces it with drying resin util the whole thing seizes.
Rebuilding is a true pain in the back as it is a 180V DC motor with build in rectifier and regulator to run on 220V AC mains.
Things I tried so far:
Adding a good amount of high temperature grease bewtween oil seal and motor housing - only a marginal longer service time was achieved.
Making a custom sleeve to go over the motor shaft that is glued onto it - worked well, or so I thought until I realised the silicone oil content in the oil slowly destroys all gues I tried so far.
Adding a shim disk right on top of the bearing - this worked best so far and almost doubled the time until the motor failed. Downside is that it takes me over 4 hours to fully rebuild a motor just to get said dik in and I have no replacements anymore.
It was suggested to me to set the back of the motor slightly higher than the front so the oil would not go anywhere near the bearing.
This I tried to implement about 8 weeks ago and as the motor got noisy last week I took it all apart for a service again.
Despite the motor mounted at an angle of about 5° the oil still creeped past the shim disk and into the bearing.
So I did some simple tests with the hot oil and indeed it forms a slowly creeping film tha travels upwards on a shaft.
I guess the rotation helps here as well to spread the drops around.
And yes, last time I used "fully sealed" bearing with an build in cover and still it fails :(
I would love to try something flexible but long lasting to seal the bearing against the rest.
Something in the region of a rubbery stuff that can be applied like a sealant.
But hard enough to survive a few weeks of shaft rotations.
Are there any really sealed bearings available?
Bearings that, for example would be fine working submerged in liquid without any liquid being able to enter?
It is clearly a desing fault of the machine to make money through spare parts but that's not the point here.
I can not replace the pump as it is an intergral part of other things attached.
And not really that easy to find a pump capable of dealing with hot oil anyway.
Is there any grease available that does not turn into a liquid at these high temps and would it be possible to get ito into a bearing?
Running out of ideas here guys, so feel free to throw in whatever comes to mind even if it seems odd!
I just need a way to keep highly viscous, boiling hot oil from entering a bearing ;)