Disc rotors with permanent magnets for brushless DC motor

A permanent magnet motor for driving an autonomous underwater vehicle, said motor comprising:

• first, second, third and fourth generally cylindrical, substantially flat stators disposed in stacked relationship, said first and second stators being axially spaced and the third and fourth stators being axially spaced, each of said stators comprising a tape-wound stator coil;
• a first substantially flat, generally cylindrical rotor disposed between said first and second stators and a second substantially flat, generally cylindrical rotor disposed between said third and fourth stators, each of said rotors including, embedded therein, a plurality of permanent magnets arranged in spaced relation in an annular configuration and an iron ring disposed behind the magnets to complete a magnetic flux path between the magnets;
• a first shaft connected to said first rotor and a second, concentric shaft connected to said second rotor;
• and
• means for providing rotation of said first and second shafts, and thus of said first and second rotors, in opposite directions;
• said second shaft comprising a hollow tube having a central bore therein and said first shaft being disposed within said bore and including a portion which extends beyond the end of said second shaft that is connected to said second rotor.

A brushless dc permanent magnet motor for driving an autonomous underwater vehicle, said motor comprising:

• first and second substantially flat, generally cylindrical, ironless stators;
• first and second substantially flat, generally cylindrical rotors disposed on opposite sides of said first stator and third and fourth substantially flat, generally cylindrical rotors disposed on opposite sides of said second stator, each of said rotors including, embedded therein, a plurality of permanent magnets arranged in an annular configuration and an iron ring disposed behind the magnets so as to complete a magnetic flux path between the magnets;
• a first shaft connected to said first and second rotors and a second, concentric shaft connected to said third and fourth rotors;
• and
• means for providing rotation of said first and second shafts in opposite directions;
• said first and second stators, said second shaft and said second, third and fourth rotors including central aligned bores therein, said second shaft extending through said bores in said stator and said fourth rotor to said third rotor and said first shaft extending through said bores in said second shaft, said fourth rotor, said second stator, said third rotor, said second rotor and said first stator to said first rotor.