Marine propulsion – Screw propeller – Shafting
Reexamination Certificate
2002-07-22
2003-09-02
Swinehart, Ed (Department: 3617)
Marine propulsion
Screw propeller
Shafting
C440S08900C
Reexamination Certificate
active
06612883
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-231355 filed on Jul. 31, 2001 the entire contents thereof is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an output shaft structure of a personal watercraft.
2. Description of Background Art
Personal watercrafts of a type shown in
FIG. 12
have been known, wherein an engine
1
is mounted on a watercraft
2
with a crankshaft
1
a
of the engine
1
extending along the longitudinal direction of the watercraft body
2
, and a shaft
3
a
of a jet pump
3
is coupled via a coupler
4
to an rear end
1
b
of the crankshaft
1
a
in such a manner as to be disposed on an extension of the crankshaft
1
a.
In these personal watercrafts, power from the crankshaft
1
a
of the engine
1
is transmitted to the jet pump
3
via the shaft
3
a,
to propel the watercraft body
2
.
The above-described personal watercrafts have been frequently used for the purpose of enjoying leisure sport, and as a result of immoderate running of the watercrafts, water may be somewhat permeated in the watercraft body
2
.
Accordingly, in the above-described related art personal watercraft, there has arisen a problem that water permeates into the watercraft body
2
and comes in contact with the coupler
4
, is dispersed in the watercraft body
2
by a centrifugal force of the coupler
4
having a diameter larger than that of each of the crankshaft
1
a
and the shaft
3
a.
Further, in the personal watercrafts of this type, piping for taking off cooling water is connected to a portion, on the upstream side from an impeller, of the jet pump, and cooling water is supplied to the engine or the like via the piping. As a result, there problems have arisen wherein the piping may interfere with the coupler
4
having a large diameter, and that the piping is liable to deteriorate due to the fact that the piping is exposed to water (particularly, sea water) dispersed by the centrifugal force of the coupler
4
.
SUMMARY AND OBJECTS OF THE INVENTION
Accordingly, a first object of the present invention is to solve the above-described problems and to provide an output shaft structure of a personal watercraft, which is capable of preventing the dispersal of water in a watercraft body, preventing interference of piping with a coupler, and preventing the piping from deteriorating.
Two-cycle engines have been used as power sources of general personal watercrafts. However, in recent years, to meet a requirement to lower environmental pollution, personal watercrafts using four-cycle engines as power sources have been proposed (Japanese Patent No. 2880691).
Outputs of four-cycle engines are smaller than those of two-cycle engines as compared with the same displacement, and to cope with such an inconvenience, it has been examined to develop personal watercrafts in which engines with turbo-chargers are mounted. For example, the present inventor has already proposed, in Japanese Patent Laid-open No. 2001-140641, a personal watercraft in which an engine with a turbo-charger is mounted.
A turbo-charger has a relatively large weight, and therefore, from the viewpoint of keeping a good weight balance of a watercraft, the turbo-charger may be desired to be provided near an engine, more specifically, immediately behind the engine. Even in Japanese Patent Laid-open No. 2001-140641, a turbo-charger is disposed immediately behind an engine
2
, and consequently, the turbo-charger is disposed immediately over a coupler.
Such a personal watercraft provided with a turbo-charger, however, has an inconvenience wherein, as described above, water dispersed by the coupler directly comes into contact with the turbo-charger, so that a casing of the turbo-kept charger kept at a high temperature is liable to be thermally fatigued.
Accordingly, a second object of the present invention is to provide an output shaft structure of a personal watercraft, which is capable of suppressing a casing of a turbo-charger from being thermally fatigued.
To achieve the above first object according to the present invention there is provided an output shaft structure of a personal watercraft, wherein an engine is mounted on a watercraft body with a crankshaft of the engine extending along the longitudinal direction of the watercraft body and a shaft of a jet pump is coupled via a coupler to a rear end of the crankshaft in such a manner as to be disposed on an extension of the crankshaft. The output shaft structure includes a coupler cover that is provided for covering the coupler, and piping for cooling water, which is communicated to the jet pump, is fixed onto the coupler cover.
To achieve the above first and second objects of the present invention a turbo-charger is disposed over the coupler, and the piping is fixed onto the coupler cover at a position between the coupler cover and the turbo-charger.
To achieve the above second object of the present invention there is provided an output shaft structure of a personal watercraft, wherein an engine is mounted on a watercraft body with a crankshaft of the engine extending in the longitudinal direction of the watercraft body, a shaft of a jet pump is coupled via a coupler to a rear end of the crankshaft in such a manner so as to be disposed on an extension of the crankshaft, and a turbo-charger is disposed over the coupler. The output shaft structure includes a coupler cover formed into an approximately inverse U-shape in cross-section that is provided for covering the coupler, and the coupler cover is turnable around the shaft of the jet pump.
According to the present invention a rear portion of the coupler cover is connected to a bearing member for turnably supporting the shaft of the jet pump on the watercraft body, a breather hose and/or a grease supply hose are/is connected to the bearing member, and a cutout portion for allowing the turning of the coupler cover without interference with the breather hose and/or grease supply hose is formed in the rear portion of the coupler cover.
According to the output shaft structure of a personal watercraft of the present invention an engine is mounted on a watercraft body with a crankshaft of the engine extending along the longitudinal direction of the watercraft body and a shaft of a jet pump is coupled via a coupler to a rear end of the crankshaft in such a manner as to be disposed on an extension of the crankshaft. This output shaft structure includes a coupler cover that is provided for covering the coupler, and piping for cooling water, which is communicated to the jet pump, is fixed onto the coupler cover. With this structure, even if water, which has been permeated in the watercraft body and comes in contact with the coupler, is dispersed by the coupler, the water thus dispersed can be blocked by the coupler cover provided for covering the coupler.
Since the coupler is covered with the coupler cover, the piping for cooling water does not interfere with the coupler.
Since the dispersal of water is blocked by the coupler cover, the piping is exposed to water to a lesser extent, with a result that the piping is less deteriorated.
Since the piping is fixed on the coupler cover, that is, in a state being floated from the bottom shell, the piping is less exposed to water having been permeated in the watercraft body. As a result, it is possible to more certainly prevent deterioration of the piping.
According to the output shaft structure of a personal watercraft according to the present invention a turbo-charger is disposed over the coupler, and the piping is fixed onto the coupler cover at a position between the coupler cover and the turbo-charger. Accordingly, the output shaft structure has the following functions and effects:
Since the dispersal of water by the coupler is blocked by the coupler cover, the turbo-charger is less exposed to water dispersed by the coupler. As a result, it is possible to improve durability of the turbo-charger.
Also, since the pipin
Fuse Tomohiro
Gokan Yoshitsugu
Honda Giken Kogyo Kabushiki Kaisha
Swinehart Ed
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