Newsgroups: comp.robotics
Path: brunix!uunet!usc!news.bbn.com!noc.near.net!wpi.WPI.EDU!rkh
From: rkh@wpi.WPI.EDU (R Kurt Heinzmann)
Subject: Re: Underwater Motors
Message-ID: <1992Mar20.135919.13606@wpi.WPI.EDU>
Organization: Worcester Polytechnic Institute
References: <1992Mar19.155747.12993@sagpd1> <1992Mar20.021856.6832@netnews.whoi.edu>
Date: Fri, 20 Mar 1992 13:59:19 GMT
Lines: 13

In Article: 2004, ulrich@canberra (Nathan Ulrich) wrote:

>
>Currently, Alvin and Jason use thruster motors and controller electronics  
>immersed in compensating fluid.  As was discovered during Alvin's early years,
>conventional brush motors can cause problems: the commutation brushes tend to 
>hydroplane at high speeds and arc.  The resulting carbonized oil is conductive
>and finds its way into awkward places.  Instead we use brushless motors and  
>either Hall effect sensors or brushless resolvers for electronic commutation.

An aside: Some automobiles (early 1970's fuel-injected Volvos for example)
use a rotary fuel pump containing of a DC brush motor immersed in a small
reservoir at the bottom of the fuel tank!
