Ships – Steering mechanism – Fluid pressure
Reexamination Certificate
2002-06-07
2004-09-07
Swinehart, E. (Department: 3617)
Ships
Steering mechanism
Fluid pressure
Reexamination Certificate
active
06786167
ABSTRACT:
TECHNICAL FIELD
This invention relates to a propulsion system for boats such as a boat to run a shallow, for example, a carrier or a houseboat, or a craft equipped with an auxiliary propulsion system, for example a yacht.
BACKGROUND ART
Japanese Patent Application Laying-Open Publication No. Hei-6-219389 has disclosed a propulsion system for a wind-powered sailing boat that employs, upon entry into or departure from a port or when in a calm, an auxiliary propulsion system having a propeller projecting from the bottom of the boat. Japanese Patent Application Laying-Open Publication No. Hei-6-107280 has disclosed a boat propulsion system of a counter-rotating double-propeller type in which swirling streams generated by a fore propeller are rectified into straight streams by an aft propeller.
Propulsion systems for boats to be propelled by a propeller and steered with a helm to change the direction of course like above are allowed to be relatively simple in arrangement for acquisition of a propelling force to be great, and adapted for transportation of heavy materials, subject to the provision of a shaft projecting from the bottom of boat in the water for mounting the propeller, which has the following problems:
(1) The propeller may bite sands or rock in a shallow, or have string-like drifting matters bound thereon, with a damage to the propeller or the shaft.
(2) In the case of a yacht, the propeller shaft may act as a fluid resistance to the water, constituting a hindrance to the travel speed. A drive for the propeller may have noisy rotation sounds, as it has a clutch disengaged when sailing.
(3) The boat needs to be brought onto the shore for repair or replacement of the propeller.
To this point, Japanese Utility Model Application Laying-Open publication No. Hei-6-61695 has disclosed a propulsion system for boats, which has a swirling vortical casing incorporated in a hull, with a suction inlet and a delivery outlet confronting the bottom, and in which water is drawn by suction at from the suction inlet, to an impeller installed thereabove, where it is pressurized and converted into swirling streams, which are discharged as jets from the delivery outlet to produce a propelling force, while the vortical casing is rotatable about a vertical axis to change the direction of course, with advantageous adaptation for travel such as on a shallow.
Propulsion systems for boats with arrangement like above are adapted, without projections from the bottom, for travel on a shallow, and with provision of the vortical casing turnable to effect backward and transverse travels, for approach to and departure from a pier, subject to the following problems:
(4) Pressurized swirling streams fill the casing, to be discharged as jets, needing a conversion from kinetic energy of the impeller to energy for pressurizing streams to be swirled and a conversion from the pressurizing energy to kinetic energy of jets to be discharged, with losses of energy decreasing efficiency.
(5) The area effective for horizontal jet discharge is kept from being increased in comparison with the casing size, with a low propulsion efficiency in the horizontal direction.
(6) Upon switch between forward and backward travels, an entirety of the casing integrated with the delivery outlet is turned to change the direction, which is heavy, and needs the system to be full-scaled.
DISCLOSURE OF THE INVENTION
This invention has been made with the above-noted problems in view, and it is an object to be solved by the invention, to provide a propulsion system for boats with an incorporated impeller capable of switch between forward and backward travels without turning an impeller casing.
According to an aspect of the invention, in a propulsion system for boats, a propelling machine is configured curved-tubular, on a bottom of boat, with a front casing having a suction inlet opening fore to water, an impeller casing having an impeller inscribed thereto, and a rear casing having a delivery outlet opening aft to water, and the impeller inscribed to the impeller casing is forward and reverse rotatable, whereby water drawn by suction from the front casing and pressurized water to be discharged as jets from the rear casing are changeable in water stream directions inside the propelling machine, as the impeller is rotated forward or reverse, allowing for the boat to have a switched travel direction between forward travel and backward travel, with a great propelling force obtainable by discharging jets of pressurized water into the water.
The impeller inscribed to the impeller casing may preferably be configured as a counter-rotating double impeller comprising a front impeller and a rear impeller, whereby a greater propelling force than by a single impeller is obtainable with an improved suction performance due to water streams in travel and an improved delivery performance due to counter rotation of double impellers.
The impeller inscribed to the impeller casing may preferably comprise axial flow blades, whereby extended blade surfaces can exert increased pressurizing forces on water in forward and reverse rotations.
In particular, as the counter-rotating double impeller has axial flow blades, swirling streams of water pressurized at the front impeller can be guided onto blade surfaces of the rear casing, with increased push-in pressures, to be converted into straight streams by the rear impeller, where they are additionally pressurized.
The impeller casing and the front casing and the rear casing connected to front and rear ends of the impeller casing may preferably have flow paths thereof substantially identical in size of inside diameter, whereby discharge power of pressurized water can be substantially equalized between forward rotation and reverse rotation, allowing for the boat to have a propelling force of forward travel, even in backward travel.
The impeller casing may preferably be configured arcuate, and a drive shaft with the impeller fixed thereon may preferably be supported by bearings disposed on front and rear peripheral walls of the impeller casing, whereby the drive shaft with the impeller fixed thereon can be evenly supported, with reduced vibrations.
The impeller casing may preferably be configured cylindrical, and a drive shaft with axial flow blades fixed thereon may preferably be supported by a bearing support connected to a rear end of the impeller casing and a bearing on a side wall of the front casing, whereby vibrations can be reduced, allowing the propelling machine to be compact, as well.
The suction inlet of the front casing and the delivery outlet of the rear casing may preferably have plural rectification vanes, respectively, whereby water streams drawn by suction are guided into the front casing, and swirling water streams are rectified to be discharged, with an improved propelling performance, while preventing foreign matters from in flowing. If rectification vanes of the front casing are blocked with foreign matters, the impeller can be reverse rotated to wash off the foreign matters blocking the rectification vanes.
The front casing may preferably have a suction flow path inclined fore, and the rear casing may preferably have a delivery flow path inclined aft, whereby suction of water streams in travel as well as aft discharge of jets into the water can be performed with an increased propelling force, allowing an application to a large-scale boat such as a carrier or yacht.
The front casing and the rear casing of the propelling machine may preferably be connected or fastened at lower ends thereof to fixing flanges, and the fixing flanges may preferably be detachably attached to openings of the bottom of boat, whereby the structure can be compact without projections at the bottom of boat, with possible noise reduction. The propelling machine can be configured as a unit attachable to and detachable from the boat bottom.
The impeller casing may preferably be separable fore and aft, whereby the impeller casing with the inscribed impeller can be assembled or disassembled with ease, facilitating the cleaning in
Greenblum & Bernstein P.L.C.
Ishigaki Company Limited
Swinehart E.
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