Marine propulsion – Jet drive – Having means to prevent clogging
Patent
1997-04-21
1999-11-23
Basinger, Sherman
Marine propulsion
Jet drive
Having means to prevent clogging
440 42, 440 47, B63H 1101
Patent
active
059890835
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
This invention relates to a water jet propulsion device for vessels, and particularly, to a propulsion device which in high-speed travel reduces the roll of a vessel body as well as the cavitation, and has improved travelling performance.
BACKGROUND ART
As conventional propulsion devices for vessels of this type, there are known ones (for example, Japanese Utility Model Publication No. 1-27517) in which the propeller is made like a leaf, a plurality of those propellers are arranged on a propeller shaft, and the propellers have outer tubes provided on outer peripheral parts thereof for giving pressures.
Moreover, there is described in the Specification of Japanese Patent Application Laid-Open Publication No. 5-270486 a device that has a rotatable guide vane provided at a suction inlet of a suction duct, for changing the direction of inflowing water to the suction duct. Further, the Specification of Japanese Utility Model Publication No. 1-29200 has described therein also a device provided with a guide vane for guiding external water to a fin projected under a suction inlet. Furthermore, in Japanese Patent Publication No. 56-40078 for example, there is described also a device in which, when the propulsive force is reduced with drift matters adhering to a grid of a suction inlet, a fork-like member is rearwardly rotated to remove the drift matters.
Still more, there is described in Japanese Patent Application Laid-Open Publication No. 5-278683 also a propulsion device in which a deflection plate is provided at a bottom opening of a steering column, and jet water is frontwardly deflected with a rotatable flap.
However, in conventional water jet propulsion devices, although high-speed travel is permitted, as the blade width of an impeller is short, there is a problem that vortices occur with an increase in number of revolutions of the impeller. Still less, as the travel speed becomes high, the inflow rate of water incoming to a suction duct at a headway direction side decreases, developing low-pressure stream regions, causing cavitation phenomena on blade surfaces of the impeller, so that there may be vibrations and noises and a concurrent roll. And, in a device which has as a measure for prevention of cavitation a mobile guide vane provided at a suction inlet for changing the inflow direction to a suction duct, it may constitute an obstacle to inflowing water in high-speed travel. And, in a device which has a guide blade provided outside a suction inlet, though being able to increase the inflow rate to a suction duct, it may constitute a water fluid resistance, as the vessel moves astern or makes a turn, failing to achieve a rapid directional change.
Further, in a device provided with a grid at a suction inlet, although it has a favorable removability to solid bodies such as a driftwood, those drift matters which have a flexible nature may adhere to the grid or flow into a suction duct, binding an impeller, with a lowered performance causing a reduced propulsive force or a failure to travel. And, in a device in which adhering drift matters are removed from a grid, there is needed a speed reduction of a vessel, in addition to a manual operation. Yet less, in a device which has at a bottom part of a steering column a deflection plate provided for a reverse propulsion guide, it may constitute a water fluid resistance in high-speed travel. The invention of the present application has for its object to provide a propulsion device with improved suction performance and improved travelling performance, and a water jet propulsion device which removes drift matters adhering to a grid, while travelling, and which is small of a reduction in reverse propulsive force, when travelling astern, and free of a sudden braking nor a lateral slip, when performing a change between a forward movement and a backward movement.
DISCLOSURE OF THE INVENTION
The invention of the present application has, in a propulsion device in which a suction inlet is open at a vessel bottom part in a vicinity of a stern, water suctio
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Copy of European Search Report for EP 96 91 2237.
Ishigaki Eiichi
Oura Kazumitsu
Basinger Sherman
Ishigaki Company Limited
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