Marine propulsion – Helical screw
Reexamination Certificate
2000-07-29
2002-08-13
Morano, S. Joseph (Department: 3617)
Marine propulsion
Helical screw
C440S049000, C440S050000
Reexamination Certificate
active
06431926
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to propulsion systems for surface and subsurface vessels. More particularly, the present invention is a ribbon drive shaped as a spiral ribbon of decreasing helix angle and coil frequency within a cylinder or along the interior wall of a tubular conduit for causing water or other fluids to move with respect to the vessel when the ribbon is rotated.
BACKGROUND OF THE INVENTION
Propulsion systems for marine vessels have long been the subject of various inventions. For example, U.S. Pat. No. 475,826 to Street et al. was issued for a new form of screw propeller. The propeller was enclosed in a tube and gave water entering the tube a sternward direction. In this instance, the ribbon, surrounding a central shaft, was not of uniform diameter. However, water velocity was unaffected by this invention since the frequency of the repeating curved units of the ribbon is the same along the length of the shaft.
U.S. Pat. No. 2,568,903 to Vasser was issued for a propeller construction for watercraft. This invention describes a plurality of blades inside a cylinder, the blades having an inclined helical configuration. However, the frequency of the helical inclined blades is the same over the length of the cylinder. Thus, there is no augmented, incremental acceleration of water through the structure.
U.S. Pat. No. 3,070,061 to Rightmyer was issued for a progressive thrust propeller. This invention shows a continuous vane running along the length of a shaft. However, in this instance, the frequency of the vane along the length of the shaft varies from a higher frequency in the bow direction to a lower frequency in the stern direction. Since this invention is not encased in a tube, water will be pushed sideways away from the spinning vane, thereby losing a certain amount of the potential forward thrust for the vessel.
Certain other patents simply involve propellers of various types encased in tubes. For example, U.S. Pat. No. 5,244,425 to Tasaki et al. and U.S. Pat. No. 5,324,216 to Toyohara et al. were both issued for water-jet type units, which were units with a single curve encased in tubes.
U.S. Pat. No. 5,383,802 to Nicholson was issued for a propulsion system. The system comprises a series of separate vanes on the inside periphery of a cylinder, thereby leaving a hollow central core. When the cylinder is turned, water is drawn into the cylinder and expelled in the sternward direction, thus giving a forward propulsion to the vessel. These vanes on the inside of the cylinder are, however, generally the same frequency along the length of the propulsion cylinder, and are not continuous, thus lacking the continuous application of energy transferred to water by unitary ribbon, and perhaps being likely to produce more noise as each vane cleaves the water.
While these various systems represent certain inventive approaches to propulsion of vessels, when used in submarines or torpedoes the drive systems of such vehicles is a major source of noise production. When noise is produced in an underwater environment, detection is possible. Hence, there is a premium placed upon drive systems, especially for submarines, that allow such vessels to be driven in relative secrecy and silence.
In submarine systems, the various components have been designed to operate as quietly and as vibration-free as possible. This applies to propulsion systems as well as to the systems of fans, pumps, and other mechanical and energy transfer systems that operate within the submarine hull. In addition, hull designs have been optimized for a combination of speed, maneuverability, and quietness depending on the particular intended use. For any of these uses, the power of the propulsion device is critical, and noise suppression of the propulsion device is of equal concern. Thus, there is a continuing trend and balance that must be struck to allow a submersible to move as quickly as possible with the minimum amount of noise.
What would therefore be useful is a new propulsion system for surface vessels and for submarines in particular, which allows an increased speed of the vessel, as well as a decrease in any noise created by the propulsion system when operating in a subsurface mode.
The present invention is just such a system that differs markedly from these above inventions. The present invention generally comprises a ribbon drive of progressively decreasing coil frequency and several alternative embodiments enclosed in a propulsion tube, thereby giving directed and more effective forward motion to the vessel in a fluid environment such as water, while operating quietly and efficiently with an acoustic advantage.
SUMMARY OF THE INVENTION
As will be explained in more detail below, the present invention is a ribbon drive propulsion system and method, in several different embodiments, which allows water to be moved in channels (referred to herein as a propulsion tube) inside or adjacent to a hull, in an extremely efficient and quiet manner.
It is therefore an objective of the present invention to have a surface vessel or submarine with an improved propulsion system that is both faster and quieter than other existing systems.
It is a further objective of the present invention to create a propulsion system that operates within the hull of a submarine or surface vessel, rather than outside the hull as propellers of current systems operate.
It is a further objective of the present invention to apply a novel propulsion system to both submarines and to torpedoes, and surface vessels of all types.
The ribbon drive of the present invention comprises a series of alternative embodiments, all of which share a common concept, that is, a ribbon-like curved shape, composed of metal or other suitable material, attached either to a central axle, or alternatively to the inner surface of a cylinder or cone revolving within a tube-like space. Two or more parallel ribbon drives may be required within each cylinder or cone, to maximize balance and to minimize vibrations of a ribbon drive unit. Additionally, it is preferrable to employ the drives in conter-rotating pairs so as to cancel torsional forces on the vessel.
A key element of both the central and peripheral designs of the ribbon drive is that there is a change in the frequency of curves of the ribbon drive, which proceeds from a high frequency (i.e. many coils per unit length) to a low frequency of coils per unit length with an associatated decrease in helix angle of the ribbon-like band when viewed lateral to the axis. For example, in lateral appearance, the ribbon drive would present a tight curved helix angle, which would be nearly perpendicular to the axial flow of water entering the ribbon drive, changing/progressing rearward to a more gradual curve at a helix angle of approximately 30 degrees to the axis, although this is not meant as a limitation since other angles may also prove beneficial.
The initial tight curves of the ribbon drive draws in fluid, such as water, from all directions in front of the intake. This water has initial velocities with high radial/circumferencial components and an initial axial component. The rotating ribbon drive imparts forces on the water and the decreasing frequency of the ribbon drive changes both the direction of the applied force and the resulting water velocity. The result is a higher axial velocity component for the water at the outlet, thereby increasing the axial component of momentum in order to drive the vehicle in an axial direction.
Assume that a fluid, such as water, is moving along at a rate of speed “a.” Initial energy is imparted to water moving along the central linear axis of the ribbon drive by a high frequency coil. The amount of energy depends upon the revolutions per minute (R.P.M.) of the central linear shaft and thus of each coil of the helical shape. A unit of water upon exiting coil HF#
1
(high frequency, 1st coil) is moving at velocity “a+1. ” If a second, identical subsequent coil HF#
2
is turning at the same rate as HF#
1
, then it too,can only add “1” to
Morano S. Joseph
Olson Lars A.
Roberts Abokhair & Mardula LLC
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