Marine propulsion – Jet drive – Auxiliary use of propulsive fluid
Reexamination Certificate
2002-10-03
2004-06-22
Basinger, Sherman (Department: 3617)
Marine propulsion
Jet drive
Auxiliary use of propulsive fluid
C440S08800J, C440S08800J, C440S08900C, C440S08900C
Reexamination Certificate
active
06752671
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water jet propulsion type outboard motor, in particular, to an improvement of a water anti-splash device also serving as a water intake unit for cooling water, an exhaust system for reducing exhaust noise, and a movable screen.
BACKGROUND ART
Japanese Patent Application Laid-Open NO.9 (1997)-309492 discloses a water jet propulsion type outboard motor including an impeller that is housed within a duct having a suction port and a nozzle: water sucked from the suction port is pressurized the impeller to be jetted out from the nozzle to propel a ship. However, since the impeller of this outboard motor consists of axial flow blades, a thrust obtained with such an impeller is limited. Moreover, since the pressurized water in the duct is used as cooling water for an engine, sand flowing through the suction port gets mixed in with the cooling water for the engine.
Japanese Patent Application Laid-Open NO.11 (1999)-286297 discloses a splashproof device for an outboard motor, in which a horizontal plate type splashboard is provided between the outboard motor and a ship so as to prevent an increase in running resistance caused by water striking against the outboard motor as well as to prevent water from splashing into the ship. However, this splashproof device is not capable of preventing water splashing from the stern from striking against a side face of the outboard motor when the outboard motor is rotated to change the running direction. Therefore, this splashproof device cannot prevent resistance from being increased. Moreover, water striking against the side face of the outboard motor splashes into the ship.
Japanese Patent Application Laid-Open NO.9 (1997)-39892 discloses a water jet propulsion type outboard motor, in which a swirl water flow pressurized with an impeller is conveyed to a volute casing to be jetted out from a discharge port so as to propel a ship. However, since this outboard motor vertically sucks water from a suction port, there is a possibility that cavitation may occur due to negative pressure at the suction port while the ship is running. Moreover, exhaust gas from an engine is directed to an underwater exhaust chamber, to which high-pressure water in the volute casing is supplied, so that energy of the exhaust gas is absorbed by the water so as to deaden the noise. However, since the high-pressure water is supplied to the underwater exhaust chamber through a hole provided through the volute casing, energy loss is generated.
Japanese Patent Application Laid-Open NO.8 (1996)-253196 discloses a screen for debris removal, which is fixed over an inlet port of a suction casing so as to prevent debris floating under the water and on the water surface from being sucked inside. However, since this screen is fixed, it is necessary to remove screws, pins or the like which fix the screen in order to remove debris such as vinyl or cords passing through the screen and caught on an entry section of an impeller. Therefore, it is difficult to remove debris when a ship is on the water.
DISCLOSURE OF INVENTION
In view of the conventional problems as described above, the present invention has an object of providing a small and light-weight safety water jet propulsion type outboard motor with high propulsion efficiency.
Another object of the present invention is to provide a water intake unit for preventing sand or the like from getting mixed with cooling water, an anti-splash device for preventing an increase in running resistance due to collision of a water flow splashing from a stern against a propulsion device and for preventing water from splashing into a ship, an exhaust system for reducing exhaust noise to lower the operation noise, and a movable screen for facilitating the removal of debris or the like.
In order to achieve the above objects, a water jet propulsion type outboard motor according to a first aspect of the present invention includes: a power source; a driving system for transmitting a driving power of the power source; a curved tubular duct member fixed to a housing on which the power source is mounted, having a suction port and a discharge port; guide blades provided within the duct member, in the vicinity of the discharge port thereof; and an impeller enclosed by the duct member and rotated by the driving system, wherein an outer peripheral edge of a spiral blade of the impeller provided around its hub is close to an inner peripheral face of the duct member, and an outer peripheral distal end portion of the impeller extends toward the suction port.
In the above structure, since the impeller is enclosed within the duct member for protection, the impeller does not come into contact with obstacles such as sand or rocks. Therefore, according to the outboard motor including the impeller, the safe running of a ship can be provided even in shallows such as in the vicinity of a shoreline or on a river.
Moreover, since the duct member has a curved tubular shape, a length of the duct member can be reduced, thereby reducing the outboard motor in size as well as in weight. Therefore, since the outboard motor does not protrude backward from the ship, the amount of band-shaped objects caught on the outboard motor or the contact with the driftwood or the like is decreased, thereby increasing the working rate and enhancing the safety of the outboard motor.
Since the outer peripheral edge of a spiral blade is close to an inner peripheral face of the duct member so as to give an axially symmetrical energy to a fluid in a cross section vertical to a rotation axis of the impeller, balance efficiency is improved. Moreover, the outer peripheral distal end portion of the spiral blade extends to the side of the suction port to form wide suction port and flow path of the impeller, floating objects are not caught on the spiral blade even when the floating objects flow into the duct member. Moreover, even when string or the like flows into the duct member, the string does not wind itself around the long blade face of the spiral blade. As a result, the suction performance is improved.
A water jet propulsion type outboard motor according to a second aspect of the present invention is the outboard motor of the first aspect, wherein the outboard motor further includes a cooling water system for cooling the power source, including: a pump for pumping up water from outside; first and second water channel systems for guiding water from outside into the pump; and a third water channel system from the pump via the power source to the outside.
A water jet propulsion type outboard motor according to a third aspect of the present invention is the outboard motor according to the second aspect, wherein the first water channel system includes: a water suction port provided on an inner surface of the duct member between the impeller and the discharge port; a straight tubular path having the water intake port on its end, penetrating through the duct member; a first water channel branching from the straight tubular path, for guiding water into the pump; and a strainer provided in the straight tubular path so as to be detachable from the outside, and wherein the second water channel system includes: a water intake unit for taking in water from outside; and a second water channel for guiding water from the water intake unit into the pump.
In the above structure, the cooling water system for cooling the power source includes two water channel systems for guiding cooling water into the pump, that is, the first and second water channel systems. The first water channel system takes water in through the water intake port provided on the inner wall of the duct member between the impeller and the discharge port, whereas the second water channel system takes water in from outside. During the normal running of the ship, water pressure within the duct member between the impeller and the discharge port is increased by the rotation of the impeller. Thus, the cooling water is mainly taken from the water intake port of the first water channel system. During the runnin
Goto Takahiro
Ishigaki Eiichi
Ishimoto Koji
Ishimura Kazuhisa
Oura Kazumitsu
Basinger Sherman
Greenblum & Bernstein P.L.C.
Shigaki Company Limited
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