US 5,229,677 AGranted

Electric propulsion motor for marine vehicles

AssigneeNewport News Shipbuilding and Dry Dock Company

InventorsThomas B. Dade, Kenneth W. Leiding, Peter P. Mongeau, Mark S. Piercey

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Abstract

An improved electric propulsion motor for marine vehicles. The motor has an axial gap design with a disk-shaped rotor and two disk-shaped stators. Within the large, open diameter of the motor a sound isolation coupling is disposed between two annular plates that connect the rotor to the propeller shaft. Circumferential thrust bearings counter and distribute electrical and mechanical forces in the motor to maintain the position of the rotor relative to the stators. A journal bearing supports the rotor. Noise reduction is greatly enhanced by the implementation of staggered stators, skewed stator slots, skewed field poles and a current control system that compensates for torque pertubations that are a repeatable function of shaft angle.

Claims35

Dependent claims

An electric propulsion motor for marine vehicles comprising:

a disk-shaped rotor and two coaxial disk-shaped stators, said rotor being separated from each of said stators in an axial direction by an air gap;
said rotor including a plurality of permanent magnets that produce a first magnetic field;
each stator comprising an armature winding that is connected to a source of electrical current to produce a second magnetic field, said first and second magnetic fields being capable of interacting to create an electromagnetic torque;
means for coupling said rotor to a propeller shaft for transferring said torque from said rotor to said shaft, and means for detecting the angle of said shaft;
a current control means for receiving a current control signal and for employing pulse width modulation to control said source of electrical current;
said current control means including means for storing compensation information related to torque variations that are a function of shaft angle;
said current control means further including means connected and responsive to said shaft angle detecting means for selecting said compensation information as a function of shaft angle and means for combining said compensation information with said current control signal to control said source of electrical current such that the torque variations that are a function of shaft angle are minimized;
and
wherein said means for coupling said rotor to said propeller shaft includes means within the motor for isolating said shaft from sound produced by said motor.

6 more elements

Dependencies are inferred from the claim text.