Who makes DC motors which run even when immersed in water?

Question

I darkly remember an article about a company which builds electric motors which run fine even when you "drown" them in water, with anchors and everything being perfectly friendly with the element.

Does anybody know anything about that?

Thanks.

Answer 1

Simple, seal the motor so the water can't get in.
Or create an magnetic induction drive.

How else does a submarine drive the propeller screws? There are some pretty tight seals around the drive shaft that keeps the water away from the motor.

If water gets inside of a motor it can create a short circuit since water is conductive, and salt water is very conductive. But the coils and magnetic where the main mass of the motor it isn't the part that is at risk. The armature is what has to be sealed and isolated from the water. Armatures are usually thin strips of metal that are bent to contact the shaft of the motor. When the electricity is sent through the armature it goes into the coils on the motor. The contact between the armature and the start of those coils are separated so the motor is given a series of pulses that drive it. The distance between the armature and the shaft where the coils start has to be very close. Here water can short out the motor. The coils can be separated enough that it is not likely that water will short them out.

However, for the best operation of an electric motor the entire motor should be sealed against the water.

There is a way to have a motor turn a shaft without using a complete shaft, and totally isolating the motor from the water; induction. Take a motor and hook it to a shaft then put a large magnet at one end of the shaft, far enough away from the motor to not affect it. Outside you would have another shaft with a magnet on it that is connected to the propeller? In this case the revolution of the interior magnet will revolve the outer magnet causing the outer shaft to turn without being connected to the inner shaft. Clearly you would need a nonmagnetic material between the two magnets like aluminum. Maybe this is the idea you are looking for.

Answer 2

All electrical devices have rating of some type. For DC motors, some of them are voltage, current, torque and speed. If you apply a voltage or current greater than the rating, the motor will eventually fail.

Answer 3

search for submerge water pumps, you will find electric motors in vary sizes. The point is not just sealing the electric part from water, it also how to remove the heat generated with the sealing.