Marine propulsion – Screw propeller – Having transmission
Patent
1992-06-15
1994-05-17
Kashnikow, Andres
Marine propulsion
Screw propeller
Having transmission
440 86, 192 331, 74DIG8, B63H 2326
Patent
active
053122771
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention generally relates to driving systems for boats having so called surface water driving propeller assemblies, and the invention more particularly relates to such a driving system, in which the driving motor is a motor with a supercharging assembly, particularly a supercharged Diesel-motor (turbo-Diesel) or a motor having a compressor supercharger.
BACKGROUND OF THE INVENTION
A surface water driving propeller assembly is a type of boat gear, in which the gear is mounted in the stern of preferably planing boats and in which the propeller assembly with its gear body projects essentially horizontally backwards (when the boat is planing) outside the stern, and which drives a propeller with an essentially straight shaft. Gears of this type are mounted in such a way, that the gear housing, when the boat is driven at speeds above a certain minimum speed, which corresponds to the lowest planing speed, is substantially parallel with the water surface and close to the water surface and in which the propeller assembly with its propeller dips into the water with only about half its height. Some propeller blades are then positioned in water, whereas other propeller blades are being ventilated in the air above the water surface. Propellers designed for this type of gear are consequently larger and/or have a larger pitch than conventional underwater-working propellers, usually at least a 15% larger diameter and pitch, because only some of the propeller blades exert a propulsion power below the water surface, and also the propellers must rotate considerably slower than conventional underwater-working propellers in order to attain the best driving conditions. Various examples of gears with surface water driving propellers are shown in European patent specification 37.690 (Arneson) or in Swedish patent accplications 8804295-7 and 8804296-5 (Thiger).
When the boat is immobile and before it has accelerated to its planing speed, all the propeller assembly and the better part of the gear body are positioned below the water surface, and a very large force from the motor is required, if the motor is to be able to accelerate the boat up to its planing speed, at which speed the propellers will be able to start working in the desired way, particularly because the propeller assembly is considerably larger and has a larger pitch than conventional underwater-working propellers.
Gears with propeller assemblies of the surface water-driving type are very different from underwater-driving propellers, i.a. since the propeller in the planing speed works in air as much as 50-70% and is considerably larger and usually has a considerably larger pitch than the corresponding underwater-working propellers and since the propeller drives the boat through a pressure force from the rear side of the propeller, while conventional underwater-working propellers propel the boat through a suction force on the front side of the propeller in substantially the same way as a sailing boat, when the wind comes ahead to port, is propelled through the suction force from the front side of the sail This is the main reason for the absence of a cavitation and a suction downwards of air from the water surface as far as a surface water-driving propeller goes, which is quite common as to conventional underwater-working propellers. Thus, it is possible as to surface water-driving propellers, already when the boat is immobile, to exert an initial force on the propeller, which corresponds to a maximum torque from the motor. In this way a boat with a surface water-driving propeller can be accelerated very strongly, and in practice such propeller assemblies, in comparison with underwater-driving propellers, prove to attain a speed increase of as much as 30-40%.
When motors, particularly Otto-engines, without turbo-charging assemblies are used, the required large initial force can often be obtained through a large gas input, but when using driving motors provided with supercharger assemblies such as turbo- or compressor-charge-assem
REFERENCES:
patent: 1667475 (1928-04-01), Kasley
patent: 4305710 (1981-12-01), Schneider
patent: 4378219 (1983-03-01), Tanka
patent: 4820209 (1989-04-01), Newman
patent: 5018996 (1991-05-01), Newman
patent: 5108324 (1992-04-01), Adams
Bartz Clifford T.
CPS Drive
Kashnikow Andres
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