Marine propulsion – Screw propeller – Having means to control flow around propeller
Patent
1995-01-24
1996-09-24
Basinger, Sherman
Marine propulsion
Screw propeller
Having means to control flow around propeller
440 75, 440 78, 440 83, B63H 128, B63H 512
Patent
active
055585485
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a propulsion unit for marine vessels, the unit comprising a housing connected to the hull of the vessel and the housing incorporating a propeller shaft provided with a surface-breaking propeller.
BACKGROUND OF THE INVENTION
Until now, known propulsion units of this type, whether they be purely outboard motors or so called inboard propulsion units with totally submerged or surface-breaking propellers, have had propeller shafts which, when the boat is travelling straight ahead, have been aligned with the longitudinal extension of the boat. In other words, the propeller shaft has always been parallel to the usual steer fin on outboard motors and inboard propulsion units.
When powered by surface-breaking propellers, water is accelerated both in the axial direction and sideways, whereby the sideways forces generated by the sideways acceleration in previously known propulsion units has solely resulted in pure losses of kinetic energy, which is comparable with the rotation of the slip stream in conventional propellers. The resultant of the propeller pressure force in the longitudinal direction and the sideways force can, when large sideways forces are present, deviate so much from the longitudinal direction that it has been necessary to compensate for this by setting the rudder of the vessel (with fixed drive units), or the entire propulsion unit (with simple steerable units), at an angle, with consequential increase in the flow resistance. In twin installations, the counter-rotating propellers do not require any oblique setting of the propulsion unit or rudder since the side forces act in opposite direction and do not generate any steering forces, though the losses remain and the side forces must be taken up in steering components, tie-rods and suspension members.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a propulsion unit of the previously mentioned type in which the above mentioned losses and the loading of, for example, the tie-rod arrangements and associated components can be eliminated.
This is achieved in accordance with the present invention in a manner such that, in the horizontal plane, the propeller shaft forms an angle to a vertical plane of symmetry of a flow-control body connected to, or integral with, said housing, said body being intended to be aligned with the longitudinal extension of the vessel when the vessel is travelling in a straight line. With steerable propulsion units having a steer fin, the propeller shaft is angled primarily with respect to the steer fin so that the fin is aligned with the longitudinal extension of the vessel when the propeller shaft is obliquely set, so that the resultant of the propeller pressure force and the propeller side force will act essentially in the longitudinal direction.
In a preferred embodiment of the propulsion unit according to the invention, two oppositely rotating propeller shafts are located in the housing in a common, substantially horizontal plane. The shafts form an included angle which is bisected by a steer fin.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail in the following with reference to the embodiments shown in the attached drawings in which
FIGS. 1 to 5 show schematic plan-views of the hull of a vessel with five theoretical alternative embodiments for a drive arrangement,
FIGS. 6-8 show schematic elevational views of a steerable propeller drive unit having three alternative angular drive arrangements,
FIG. 9 is a schematic elevational view of a fixed propeller drive unit with a straight distribution gear arrangement,
FIG. 10 is an elevational view of a propulsion unit in the form of an outboard motor and
FIG. 11 is a schematic elevational view of a steerable propulsion unit having four propellers.
DETAILED DESCRIPTION OF THE INVENTION
In FIGS. 1-5, reference numeral 1 denotes a boathull, numerals 2 and 3 denote inboard-mounted engines and numerals 4 and 5 denote steerable outboard drive units, for e
REFERENCES:
patent: 2162058 (1939-06-01), Brush
patent: 2909140 (1959-10-01), Kiekhaefer
patent: 3368420 (1968-02-01), Alexander, Jr.
patent: 3952678 (1976-04-01), Weston
patent: 4435110 (1984-03-01), Hunkeler
patent: 4609360 (1968-09-01), Whitehead
patent: 4728308 (1988-03-01), Weismann
patent: 4775342 (1988-10-01), Connor
patent: 4810218 (1989-03-01), Iwai
Hallenstvedt Oddbjorn
Olofsson Niclas
Rydberg Anders
AB Volvo Penta
Basinger Sherman
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