Drive shaft support structure for small watercraft

Details Drive shaft support structure for small watercraft Drive shaft support structure for small watercraft

2002-08-07

2004-02-24

Morano, S. Joseph (Department: 3617)

Marine propulsion

Screw propeller

Shafting

C440S038000, C440S112000

Reexamination Certificate

active

06695656

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2001-272361, filed Sep. 7, 2001, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drive shaft support structure for a small watercraft. More particularly, the present invention relates to a drive shaft support structure for a small watercraft in which an impeller is driven by a drive shaft connected to an output shaft of an engine mounted in a boat body.
2. Description of Background Art
A conventional drive shaft support structure for a small watercraft is shown in FIG.
7
.
FIG. 7
shows an engine
1
mounted on a boat body
2
, and a drive shaft (hereinafter referred also to simply as a shaft)
4
connected to an output shaft
1
a
of the engine
1
through a coupler
3
. An impeller
5
a
of a jet pump
5
is fixed to the rear end of a shaft
4
. When the impeller
5
a
is rotationally driven by the engine
1
through the shaft
4
, water is taken in through a water intake port
2
a
provided at the bottom of the boat and is jetted from a nozzle
5
b
, whereby the boat is propelled forward.
The boat body
2
is provided with a cylindrical portion
2
b
through which the shaft
4
passes and which extends from the outside of the boat toward the engine
1
, and a support portion
2
c
for supporting a rubber dampered bearing body
6
rotatably supporting the shaft
4
on the engine
1
side.
The bearing body
6
includes a metallic cylindrical member
6
a
, a bearing member
6
b
mounted in the cylindrical member
6
a
, a rubber damper portion
6
c
formed integrally with the outer circumference of the bearing body
6
, and a reinforcement member
6
d
integral with the rubber damper portion
6
c
. The bearing body
6
is fixed to the support portion
2
c
by passing a bolt
6
e
through the reinforcement member
6
d
, mating a nut
6
f
to the bolt
6
e
, and fastening the nut
6
f.
A tubular body
7
is disposed in an intermediate position between the bearing body
6
and the support portion
2
c
. The tubular body
7
includes a tubular portion
7
a
extending toward the tubular portion
2
b
of the boat body
2
and a flange portion
7
b
. The tubular body
7
is fixed to the support portion
2
c
by fastening the flange portion
7
b
to the bearing body
6
with a bolt
6
e
and nut
6
f.
The rear end of the tubular body
7
and a tip end portion of the tubular portion
2
b
of the boat body
2
are connected to each other by a rubber sleeve
8
. In this condition, both ends of the rubber sleeve
8
are fastened by ring-shaped clamps
9
,
9
.
According to this conventional shaft support structure, the shaft
4
can be rotatably supported by the rubber dampered bearing body
6
to absorb some of the oscillation of the shaft
4
.
While some penetration of water W inside the boat body
2
can be prevented through the tubular portion
2
b
of the boat body
2
can be prevented to a certain degree by the rubber sleeve
8
, the tubular body
7
, and the rubber dampered bearing body
6
, it is difficult to ensure. More specifically, with this conventional structure, water W tends to penetrate into the boat body
2
through the tubular portion
2
b
at one or more of the following points:
the connection portion C
1
between the tubular portion
2
b
and a rear end portion of the rubber sleeve
8
;
the connection portion C
2
between a tip end portion of the rubber sleeve
8
and a tip end portion of the tubular body
7
;
the joint portion C
3
between the flange portion
7
b
of the tubular body
7
and the bearing body
6
; and
the joint portion C
4
between the flange portion
7
b
of the tubular body
7
and the support portion
2
c.
In summary, it has been difficult to ensure that water will not penetrate the boat body
2
. Even if the flange portion
7
b
of the tubular body
7
and the support portion
2
c
are tightly joined to each other with an adhesive, water is still likely to penetrate at least the three portions C
1
to C
3
.
SUMMARY AND OBJECTS OF THE INVENTION
It is an object of the present invention is to provide a drive shaft structure for small watercraft which solves the at least the above problem of water seeping into the boat body through a tubular portion of the boat body.
In order to attain the above object, the present invention provides a drive shaft support structure for small watercraft, which includes an impeller in which the drive shaft is connected to an output shaft of an engine mounted in a boat body. The boat body is provided with a cylindrical portion extending from the outside of the boat body toward the engine, through which the drive shaft passes. Also provided is a rubber dampered bearing body which rotatably supports the drive shaft on the engine side so that it does not contact the cylindrical portion. The rubber dampered bearing body is supported by a support portion, and includes a rubber damper portion and a rubber cylindrical portion which extends toward the cylindrical portion, the rubber cylindrical portion being formed integrally with the rubber damper portion. The rubber cylindrical portion and the cylindrical portion are connected directly to each other.
The rubber cylindrical portion is provided with a grease supply hole for supplying grease to a water seal portion of the rubber dampered bearing body, and a grease supply hose is connected to the grease supply hole.
An engine output shaft and the drive shaft are connected to each other through a coupler having a coupler cover, the rear end of the coupler cover being supported by the rubber damper bearing body.
The drive shaft support structure for small watercraft includes the impeller driven through the drive shaft connected to the output shaft of the engine mounted in the boat body, wherein the boat body is provided with the cylindrical portion through which a drive shaft is passed and which extends from the outside of the boat toward the engine. A support portion for supporting the rubber dampered bearing body rotatably supporting the drive shaft on the engine side from the cylindrical portion is also provided. The rubber dampered bearing body includes a rubber cylindrical portion formed integrally with the rubber damper portion of the rubber dampered bearing body, and the rubber cylindrical portion and the cylindrical portion are connected directly to each other.
As a result, water which may otherwise penetrate a conventional boat body is prevented from entering the boat interior by the present invention. This is due to the fact that the present invention includes only one point where water may possibly enter, namely, the connection portion between the rubber cylindrical portion and the cylindrical portion on the boat body side. Thus, it is more difficult for water to penetrate into the boat through the cylindrical portion of the boat body than with conventional structures.
Moreover, the rubber cylindrical portion is formed integrally with the rubber damper portion of the rubber dampered bearing body, and the rubber cylindrical portion and the cylindrical portion are connected directly to each other. As a result of this structure, the number of component parts is markedly reduced as compared with the prior art. The tubular body
7
, the rubber sleeve
8
, and one of the two clamps
9
,
9
of the conventional boats become unnecessary, and thus the assembly tasks are reduced.
With the present invention, the rubber cylindrical portion is provided with the grease supply hole for supplying grease to the water seal portion of the rubber dampered bearing body, and the grease supply hose is connected to the grease supply hole. As a result, grease can be easily supplied to the water seal portion of the bearing body through the grease supply hose. This feature acts to prevent water from entering into the inside of the boat body through the cylindrical portion of the boat body.
Further as described above, the output shaft of the engine and the

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