Marine propulsion – Screw propeller – Having means to control flow around propeller
Reexamination Certificate
1999-12-21
2001-02-27
Swinehart, Ed (Department: 3617)
Marine propulsion
Screw propeller
Having means to control flow around propeller
Reexamination Certificate
active
06193573
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of marine water craft, particularly to high speed power boats utilizing a surface piercing propeller drive system mounted within a propeller tunnel formed integral to the hull of the boat, and most particularly to inclusion, within a wall of said tunnel, of a means for providing air thereto; said means being judiciously placed for linearization of the relationship between vessel velocity and engine speed.
BACKGROUND OF THE INVENTION
Surface piercing drive technology and propeller tunnels are an established art which the inventor helped pioneer having been awarded U.S. Pat. No. 4,689,026, the contents of which are incorporated herein by reference. The drive systems can be highlighted by their ability to provide enhanced boat performance by use of the surface piercing propellers while safely placing such propellers beneath the hull of the water craft.
The obvious disadvantages of the surface piercing propellers may be found in reference to U.S. Pat. No. 5,667,415 issued to Arneson. The surfacing propeller is well known for its speed, as well as its lack of thrust at low speed, overloading its power source at preplane speeds and low thrust in reverse. Arneson has successfully commercialized surface piercing propellers which position a propeller near the surface of the water at a location outward from the transom of a boat. Air is drawn into and through the propellers and through the principles of compression/cavitation the propeller is able to function according to its design characteristics, thus leading to enhanced speed and performance derived from the surface piercing technology. Disadvantages to the surface piercing technology are mainly directed to the location of the propeller which is typically at the back of the boat. This interferes with the use of the back of the boat for fishing, diving or swimming and exposes the propeller to a position that is most dangerous. Representative disclosures relating to surface piercing technology can be found in U.S. Pat. Nos. 4,645,463 and 4,909,175.
Other disadvantages are the need to rotate the drives since they operate as a rudder and the inability to operate such drive systems at low speed which became the subject of the Arneson U.S. Pat. No. 5,667,415 previously mentioned. In this registration the invention discloses the use of a shroud that is placed around the propeller which prevents “walking” of the propeller at low speed but also protects individuals or marine life from impacting the propellers.
The directing of air to the propeller while it is beneath the boat provides a known benefit and is the subject of various types of prior art such as the following: U.S. Pat. Nos. 2,434,700; 3,702,485; U.S. Pat. No. Re. 23,105; U.S. Pat. No. Re. 38,522; U.S. Pat. Nos. 130,391; 807,769; 815,270; 1,081,876, 1,117,357; 1,262,942; 1,401,963; 2,138,831; 3,450,090; 4,031,846; 4,363,630; 4,383,828; 22,080; 965,870, 1,916,597; 1,966,029; 3,793,980; 3,937,173; 4,300,889; 4,443,202; 5,141,456; 5,405,278; 5,171,175; 5,667,415; 5,679,037; 4,977,845; 4,371,350; 4,993,349; 5,482,482; 5,588,886; and 4,941,423.
What is lacking in the art is the teaching of a surface drive technology that forms air passageways that enhance surface piercing propeller operation at all speeds and conditions and that particularly provides for a linearization of the relationship between vessel velocity and engine speed.
SUMMARY OF THE INVENTION
The present invention is directed to marine vessels having a surface piercing propeller(s) in a defined enclosure. In its simplest form, the present invention provides at least one surface piercing propeller positioned within a depression, termed a tunnel, formed within the vessel's hull, which tunnel has at least one surface or wall which runs generally parallel to a longitudinal axis of said vessel and is contiguous with a bottom side of said hull and a top side of said tunnel. The wall contains at least one opening through which air is supplied. This opening is placed so as to be gradually uncovered from water as the vessel's forward speed increases. Judicious placement of the opening enables the relationship between the vessel's velocity and the engine speed to define and maintain an essentially linear relationship as the vessel accelerates from rest to its maximum velocity and during the transition from displacement mode to planing mode.
In a further embodiment, the configurations define an air induction system that allows each of the critical performance parameters to be optimized and controlled to suit the hull configuration to which it is applied. This air induction technique was developed because of the obvious advantages and disadvantages of current surfacing propeller drive systems. It was observed that the characteristics of surfacing propellers and the engines used to drive them suffered compatibility problems in their current applications. This observation lead to the need to identify and control critical design elements. The design of surfacing propellers, per se, relies upon very refined science; however their incorporation with a particular hull design requires that a degree of intuitive art be applied. The engines must follow the laws of thermodynamics and be operated in a cost effective manner; thus their operating characteristics are considered a given. In order to make the technologies compatible, it is critical that the interrelationship of their operational parameters be understood. The prior art either completely fails to address the control of air, or the mechanisms that have been employed are cumbersome and require constant operator intervention. This invention recognizes and discloses the relationship between efficient engine operation and air requirements of surface piercing propellers, and provides a method of application of this technology which results in enhanced operation of both the surfacing propeller and its prime mover.
Previous techniques have merely addressed the requirement for air, but have failed to appreciate either the need to control the amount of air supplied or the criticality of timing to the air supply/propeller relationship. The application of the parameters described herein provides the propeller with the environment required by a surfacing propeller. Engine characteristics can be compensated for by using these propeller to air relationships to assist the engine in attaining its torque and rpm design targets. The uniqueness of this invention is that it requires no moving parts, controls or operator intervention. The ability to vary the amount and timing of air to the propeller is achieved by the shape and location of the air induction system, in combination with the nature of water flow and the natural angle change that a marine vessel goes through as it transitions from static to on plane speeds. These features are molded in surfaces of the hull and can be designed to expand the operating window of the vessels it is applied to. The operational characteristics that are gained are 1) seamless transition from idle to planing speed, 2) stable speed at any sea state and throttle setting, and 3) effective reverse with directional control.
The propeller enclosing tunnel may be a single surface or it may be defined by a series of surfaces, each of which provide an enhancement to the operation of the vessel. In particular, the top of the tunnel may be formed from a flat surface which is used for mounting the propeller strut and rudder. The flat surface also eliminates the need for different left and right strut fittings and provides a uniform surface for determination of propeller blade clearance.
A second surface may be formed angular to the first surface and positioned perpendicular thereto. The second surface enhances reverse thrust by deflecting prop wash and reducing the “damming” effect typical of a flat transom vessel. A third surface is in juxtaposition to the first surface and provides an angular wall at a right angle, shaped to shield the propeller from obtaining water during high speed acceleration. T
McHale and Slavin
Swinehart Ed
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