I recently rewound a 1/4 hp single-phase induction motor used in a top-load washing machine (picture), but there's an issue: It heats like hell, from its own original design, and I rewound it exactly like the original winding.
I tested a similar motor (made for the same machine by another vendor) and the winding reached 120 °C max while centrifuging non-stop. The rewound one reached 140 °C in the same washing machine centrifuging the same load non-stop.
The insulation is class H, so while it won't burn, it won't last long either, so I'm trying to optimize the cooling from the cooling fins built on its rotor.
It should cause airflow through the windings around it, but it mostly only revolve the air above it, you can't even feel any flow around it with your hands.
The only motor I have ever seen having a really good airflow from those fins alone is this 1 hp motor I have:
As you may see, its front cover (identical to the back cover) has a curved inner part that extends closer to the fins, ending in a flat inner ring that sits about 2 mm above the rotor fins. Half of their length is covered by that ring and the other half extend inwards, as you can see in the picture.
So I thought of trying to do something similar, adding a flat ring that sat just above the fins like that, closed around by a short cylinder to prevent air from just passing above said ring and revolving above the rotor.
The difference is that my ring covered the full length of the fins and not half.
And it worked very poorly, didn't help nor improve, it reached the same max temperature with and without that.
So, what else could I try?
Maybe remodeling the fins could help?
Making taller or longer fins?