Marine propulsion device

Abstract

A marine propulsion device such as an outboard motor includes a submersible electric motor having a propeller connected directly with the drive shaft of the motor. The motor is an efficient brushless motor having symmetrical elliptical coils connected with a stator which generate magnetic flux when current is passed through the coils to rotate a rotor for driving the drive shaft. The motor is arranged in a housing having a nozzle connected with a rear portion thereof which surrounds the propeller to reduce cavitation. Cooling fins are provided on the outer surface of the housing to assist with cooling the motor and a motor controller arranged in the housing.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a marine propulsion system in the form of an outboard motor. Such motors have been used for many years to propel small vessels on protected bodies of water. The most common types of outboard motors are gas and electric. Internal combustion engines which rely on gas for fuel provide greater horsepower. However, they are noisy and contribute to pollution of the body of water on which the vessel is used. Accordingly, many bodies of water restrict the size of the gas powered motors allowed or eliminate them altogether.

[0002] Electric outboard motors are much cleaner and quieter than gas powered motors. They are particularly useful for propelling rowboats and fishing boats to maneuver the boats in shallow water and around submerged obstacles such as fallen trees. The main drawbacks with electric outboard motors are the limitation in horsepower, the amount of current required to operate them, and the heat generated by the mo...

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