Marine propulsion – Screw propeller – Having means to control flow around propeller
Reexamination Certificate
2002-08-08
2004-11-16
Avila, Stephen (Department: 3617)
Marine propulsion
Screw propeller
Having means to control flow around propeller
C440S071000
Reexamination Certificate
active
06817911
ABSTRACT:
BACKGROUND OF THE INVENTION
1. This invention relates to a motorboat propeller anti-slippage shroud.
2. Description of the Prior Art
Past and current designs of high revolution marine inboard-outboard motors, outboard motors, and respective propellers, suffer from inefficient fluid displacement ratios, resulting in an overall loss in performance and efficiency. Ideally, a ratio closest to a one-to-one is desirable, resulting in every unit of fluid being displaced by the leading edge of the propeller, is displaced at the trailing edge of the propeller. Current designs of propellers do not achieve nearly the ideal ratio due to the phenomena of “slippage”. The phenomena of slippage occurs at all speeds in which hydro-mechanical flow passing through the front of a propeller (intended to be displaced at the rear of the propeller), is in-fact, lost prematurely on the peripheral sides of the blades. Peripheral exposure of a propeller's blades, and lack of enclosure of the blades results in this phenomena. As a result, overall pressure and fluid velocity is decreased at the outflow point of a propeller. The net result is less distance obtained by the boat per each revolution of a propeller and less fuel efficiency. In addition, prior designs of motorboat propellers experience atmospheric ventilation at high speed because atmospheric gases are introduced to the peripheral edges of a propeller blade. Introduction of gaseous ventilation also decrease the overall mass and velocity of the fluid being displaced by a propeller, and again decreasing performance and efficiency, especially at high rates of revolution. Another disadvantage of the prior art is that inadvertent or accidental contact with the propeller may occur during times of revolution, resulting in personal injury. This is again due to the fact that the trailing edge and peripheral portions of a propeller's blades are exposed. Finally, should a propeller with exposed blades make contact with a submerged hard surface, catastrophic failure of a propeller can occur.
SUMMARY OF THE INVENTION
1. A motorboat propeller anti-slippage shroud used for high revolution inboard-outboard and outboard motors comprising:
(1) A motor boat propeller anti-slippage shroud for use on power boats other than sailboats
(2) A cylindrical shroud which is fixed to the lower portion of either a high revolution per-minute inboard-outboard motor, or outboard motor, for use by a speed boat, ski boat, or motor yacht (not intended for use by a sailboat)
(3) the shroud eliminating accidental access to the rear and peripheral portion of a propeller enclosed by the shroud during periods of high revolution by either individuals, or accidental encounters with submerged objects, or grounding
(4) the shroud minimizing slippage while maximizing fluid displacement input-output ratios per each revolution of a propeller, maximizing fuel economy and performance at all speeds
(5) the shroud commencing just forward of an enclosed propeller, but behind a ruder fixture, and extending rearward and behind an enclosed propeller's trailing edge by at least 12 inches to avoid accidental contact with a propeller even if a person's foot were placed directly inside the shroud
(6) the leading edge of the shroud allowing unrestricted hydro-mechanical flow to a propeller blade's leading edge, while the peripheral side of the shroud closely encompassing the entire peripheral circumference of a propeller, eliminating fluid displacement and subsequent loss of fluid from the peripheral side of each propeller blade, minimizing slippage during rates of high revolution
(7) the circumference of the shroud only slightly larger in diameter than a propeller located inside the shroud, with little distance between the shroud's inner circumference and the outer circumference of a propeller.
(8) the leading edge of the shroud is situated behind an integrated rudder as not to impede or compromise steering
(9) the shroud centered to ensure uniform distance between the surface of the inner circumference of the shroud and the outer circumference of a propeller's blades to ensure minimal slippage and maximum hydro-dynamic displacement
(10) the shroud being constructed of either cast iron, or other metallic substance, or a durable, hardened plastic composite not subject to warping or deformation
(11) means for mounting the shroud is either bolt-on method for a retro-fit model, or casted from factory during time of motor production from assembly line, directly to the lower (submerged) portion of a high revolution rate inboard-outboard motor or outboard motor
(12) the shroud not restricting adequate passage of hydro-mechanical flow to a motor's cooling system
REFERENCES:
patent: 5213525 (1993-05-01), Sanford
patent: 5352140 (1994-10-01), Schriner
patent: 5389021 (1995-02-01), Padgett
patent: 5597245 (1997-01-01), Meyerhoff
patent: 5848922 (1998-12-01), Itima et al.
patent: 6059618 (2000-05-01), Purnell et al.
Avila Stephen
Elizondo Luis
LandOfFree
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