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...

AI Technical Summary

Benefits of technology

[0004]The marine propulsion system according to the invention includes a submersible housing containing a brushless electric motor having a longitudinal drive shaft extending from the housing. An external propeller is connected directly to the drive shaft for rotation by the motor. Preferably, the motor produces a high torque output with reduced energy consumption. It includes a cylindrical stator having a longitudinal axis and defining a chamber in which a rotor is coaxially arranged. The drive shaft is connected with the rotor. A plurality of magnets are connected with the outer surface of the rotor and a plurality of symmetrical coils are connected with the inner surface of the stator. The coils are formed by winding a conductor in an elliptical configuration with the long axis of each coil being parallel with the longitudinal axis of the stator. When current is supplied to the conductors of each coil, the coils produce a magnetic flux which acts on the magnets to cause the rotor to rotate which in turn drives the propeller.

[0005]The housing includes a nozzle which extends from the rear and surrounds the propeller to reduce cavitation. In addition, the housing includes a plurality of longitudinal cooling fins arranged in spaced relation about the housing exterior surface to assist with dissipating heat generated in the housing by the motor.

Problems solved by technology

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.

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 motor.

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