Jet propulsion boat

Details Jet propulsion boat Jet propulsion boat

2002-08-13

2004-08-17

Morano, S. Joseph (Department: 3617)

Marine propulsion

Jet drive

Direction control for fluid jet

C440S047000

Reexamination Certificate

active

06776675

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-283784 filed on Sep. 18, 2001 the entire contents thereof is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a jet propulsion boat having a jet propulsion apparatus at the stern, a jet nozzle for jetting water, which is provided in the rear portion of the jet propulsion apparatus, and a steering nozzle swingably supported by the jet nozzle to adjust the direction of a stream of water jetted from the jet nozzle.
2. Description of Background Art
A jet propulsion boat is disclosed in Japanese Unexamined Patent Application No. Hei-2-254094, entitled “Forward/Rearward Travel Switching Apparatus of Water Jet Boat Propulsion Apparatus.”
FIG. 10
is a copy of
FIG. 1
of this publication with the reference numerals added to designate the parts thereof. This type of jet propulsion boat will be described in detail with reference to FIG.
10
.
FIG. 10
is a cross section of a conventional jet propulsion boat. A jet propulsion boat
100
has a jet propulsion apparatus
102
at the stern
101
. A jet nozzle
103
is provided at the rear portion of the jet propulsion apparatus
102
with an outlet
103
a
side of the jet nozzle
103
being covered with an inlet
104
a
side of a steering nozzle
104
. The inlet
104
a
side of the steering nozzle
104
and the outlet
103
a
side of the jet nozzle
103
are swingably coupled to each other by upper and lower supporting bolts
105
and
105
.
The jet propulsion boat
100
can be propelled by driving an impeller
102
a
of the jet propulsion apparatus
102
to thereby take water from an intake port
106
, jetting the water from the jet nozzle
103
, and jetting the jetted water from an outlet
104
b
of the steering nozzle
104
.
At the time of propulsion of the jet propulsion boat
100
, by swinging the steering nozzle
104
from side to side by using the upper and lower supporting bolts
105
and
105
as a center, the jet propulsion boat
100
can be turned from side to side.
In the jet propulsion boat
100
, when the steering nozzle
104
is swung from side to side by using the upper and lower supporting bolts
105
and
105
as a center, it is necessary to prevent that the inner circumference on the inlet
104
a
side of the steering nozzle
104
interferes with the outer circumference on the outlet
103
a
side of the jet nozzle
103
.
Consequently, the inner circumference on the inlet
104
a
side of the steering nozzle
104
has to be set apart from the outer circumference on the outlet
103
a
side of the jet nozzle
103
by some distance.
The outer circumference on the inlet
104
a
side of the steering nozzle
104
therefore becomes relatively large, and it disturbs the steering nozzle
104
that is disposed close to the boat bottom
101
.
When the steering nozzle
104
is positioned apart from the boat bottom
101
, the impeller
102
a
of the jet propulsion apparatus
102
is provided in a high position. Consequently, the curvature of the intake path from the intake port
106
to the impeller
102
a
increases, so that it becomes difficult to smoothly introduce the taken water to the impeller
102
a
side. For example, a cavitation occurs in the jet propulsion apparatus
102
and it hinders the jet propulsion boat
100
from being efficiently propelled.
SUMMARY AND OBJECTS OF THE INVENTION
An object of the invention is therefore to provide a jet propulsion boat which can be efficiently propelled by disposing a steering nozzle closer to the bottom of the boat.
To achieve the object, the present invention provides a jet propulsion boat including a jet propulsion apparatus driven by an engine at the stern, a jet nozzle for jetting water, which is provided in the rear portion of the jet propulsion apparatus, and a steering nozzle swingably supported by the jet nozzle so as to adjust the direction of a stream of water jetted from the jet nozzle, and the jet propulsion boat includes an outlet of the jet nozzle that is covered with an inlet of the steering nozzle, and the vertical diameter of the inlet of the steering nozzle is set to be smaller than the transverse diameter of the inlet.
By setting the vertical diameter of the inlet of the steering nozzle to be smaller than the transverse diameter, the steering nozzle can be disposed closer to the boat bottom. The jet propulsion apparatus can be accordingly disposed closer to the boat bottom with the curvature of the intake path extending from the intake port to the jet propulsion apparatus that can be flattened and with the intake path being formed in a gentle curve.
Consequently, water taken from the intake port can be smoothly directed to the jet propulsion apparatus, so that, for example, the occurrence of a cavitation can be prevented and water can be jetted efficiently.
In addition, by setting the vertical diameter to be smaller than the transverse diameter, the transverse diameter can be assured to be large. Consequently, the steering angle of the steering nozzle can be assured to a specified amount and the steering performance of the jet propulsion boat can be assured sufficiently.
To favorably propel the jet propulsion boat, the nozzle for jetting water has preferably a circular shape. In the present invention, therefore, the outlet of the jet nozzle is covered with the inlet of the steering nozzle.
With the configuration, even when the vertical diameter of the inlet of the steering nozzle is smaller than the transverse diameter, this portion can be disconnected from the water stream. Therefore, exertion of an adverse influence onto the stream of water in the nozzle can be prevented.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.


REFERENCES:
patent: 3143857 (1964-08-01), Eaton
patent: 3939794 (1976-02-01), Hull
patent: 5045003 (1991-09-01), Ikeda
patent: 5395272 (1995-03-01), Smith
patent: 5551898 (1996-09-01), Matsumoto
patent: 5649843 (1997-07-01), Elger
patent: 6102756 (2000-08-01), Michel et al.
patent: 6558211 (2003-05-01), Freitag et al.
patent: 2-254094 (1990-10-01), None
patent: 0913195 (1997-05-01), None

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