Marine propulsion – Screw propeller – Having transmission
Reexamination Certificate
1999-04-02
2001-03-06
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Screw propeller
Having transmission
C074S366000
Reexamination Certificate
active
06196887
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an outboard motor and more particularly to a reduction drive transmission for an outboard motor.
Relative low horsepower outboard motors are frequently employed as auxiliary power plants for sailboats. By low power, this generally means that the horsepower employed for such applications is something in the neighborhood of 10 horsepower or less. With these low horsepowers, however, the acceleration from standstill to the desired cruising speed can be quite slow. Also, in some instances the engine may not provide sufficient power to achieve the desired speeds.
Although this problem can be somewhat reduced by using a higher reduction ratio in the gear drive from the engine to the propeller, the desire to keep the lower unit, where the transmission resides, small generally limits the reduction ratio in the range of 1.8 to 2.4 to 1. Larger reduction ratios require bevel gears of larger diameters and this will produce a protracted lower unit. As the lower unit size increases, the hydrodynamic drag increases and thus, some of the advantage of the reduced gear ratio will be lost by the increased drag.
It is, therefore, a principal object of this invention to provide an improved marine drive transmission useable with outboard motors to provide a gear reduction greater than the bevel gear of the lower unit and which transmission is located so that it will not increase the size of the lower unit.
It is a further object of this invention to provide an improved reduction gear transmission for outboard motor that does not increase hydrodynamic drag.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in an outboard motor having a powerhead containing a powering internal combustion engine, a driveshaft housing and lower unit that contain a driveshaft. In the lower unit portion, a bevel gear transmission is provided for driving a propulsion unit driveshaft. A reducing gear transmission is provided in the connection between the engine output shaft and the driveshaft. This transmission is located above the water level when the outboard motor is attached to the transom of an associated watercraft.
REFERENCES:
patent: 4033282 (1977-07-01), Pichl
patent: 4331432 (1982-05-01), Blanchard
Knobbe Martens Olson & Bear LLP
Sanshin Kogyo Kabushiki Kaisha
Sotelo Jesus D.
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