U.S. patent application number 09/682031 was filed with the patent office on 2001-11-08 for jet propulsion system for watercraft.
Invention is credited to Ishino, Tetsuya, Ito, Kazumasa, Matsumoto, Chihiro.
Application Number | 20010039155 09/682031 |
Document ID | / |
Family ID | 16770372 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010039155 |
Kind Code |
A1 |
Ito, Kazumasa ; et
al. |
November 8, 2001 |
Jet propulsion system for watercraft
Abstract
A jet propelled watercraft having an improved extension assembly
for dampening pulsations from the impeller of the jet propulsion
unit and also for mounting the jet propulsion unit. The structure
simplifies the overall assembly and permits individual tuning with
conventional units.
Inventors: |
Ito, Kazumasa;
(Hamamatsu-shi, JP) ; Ishino, Tetsuya;
(Hamamatsu-shi, JP) ; Matsumoto, Chihiro;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
ERNEST A. BEUTLER
ATTORNEY AT LAW
500 NEWPORT CENTER DRIVE
SUITE 945
NEWPORT BEACH
CA
92660
US
|
Family ID: |
16770372 |
Appl. No.: |
09/682031 |
Filed: |
July 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09682031 |
Jul 12, 2001 |
|
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|
09630668 |
Aug 2, 2000 |
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Current U.S.
Class: |
440/38 |
Current CPC
Class: |
B63H 11/08 20130101 |
Class at
Publication: |
440/38 |
International
Class: |
B63H 011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2000 |
JP |
2000-210831 |
Aug 4, 1999 |
JP |
HEI 11-221666 |
Claims
1. A personal watercraft comprised of a hull having an undersurface
including a vertically extending bulkhead defining in part a rear
portion of an engine compartment containing a prime mover, said
hull undersurface defining at least in part a downwardly facing
water inlet opening through which water may be drawn and a curved
discharged path that curves upwardly from said water inlet opening
toward said bulkhead, a support plate fixed to the rear side of
said bulkhead, an extension housing affixed to said support plate
at one end thereof, a jet propulsion system carried by the other
end of said extension housing, said jet propulsion system
comprising an outer housing having an impeller portion, an impeller
rotatably journalled about an impeller axis in said impeller
portion and driven by said prime mover and a discharge nozzle
portion positioned rearwardly of said impeller though which the
water pumped by said impeller is discharged for propelling said
personal watercraft, said support plate and said extension housing
defining a water opening path leading in a direction parallel to
said impeller axis and having a shape that constitutes generally an
extension of the opening of an inlet to said impeller housing
portion so as to isolate the pulsations generated by said impeller,
said water opening path having a length substantially greater than
the axial length of said impeller.
2. A personal watercraft as set forth in claim 1 wherein the water
opening path includes an elastomeric sleeve for further damping
water pulsations caused by said impeller.
3. A personal watercraft as set forth in claim 2 wherein the
elastomeric sleeve is carried by the extension housing.
4. A personal watercraft as set forth in claim 3 wherein the inner
diameter of the elastic sleeve is substantially the same as and
forms a portion of the water opening path.
5. A personal watercraft as set forth in claim 1 wherein the jet
propulsion unit outer housing is detachably connected to the
extension housing.
6. A personal watercraft as set forth in claim 5 wherein the jet
propulsion unit outer housing impeller portion is detachably
connected to the extension housing.
7. A personal watercraft as set forth in claim 6 wherein the jet
propulsion unit outer housing impeller portion has a length
upstream of the impeller that forms a further part of the water
opening path.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of the
application of the same title, U.S. Ser. No. 09/630668, filed Aug.
2, 2000 and assigned to the assignee hereof.
BACKGROUND OF INVENTION
[0002] This invention relates to a jet propulsion system for a
watercraft and more particularly to an improved device for
minimizing the sounds and vibrations generated by the jet
propulsion unit.
[0003] Jet propulsion units are quite popular in connection with
the propulsion of watercraft and especially a particular type of
watercraft referred to as a "personal watercraft". These types of
watercraft generally are designed to be operated by a rider who may
carry no more than one to three additional passengers. Frequently
these passengers are seated in straddle, tandem fashion on a
longitudinally extending seat that is formed at the rear of the
watercraft with the propulsion unit being disposed beneath the
seat.
[0004] One problem particular with this type of construction can be
best understood by reference to the aforenoted copending
application. As noted therein in conventional constructions the
water inlet passage through the lower part of the watercraft hull
curve upwardly from their inlet opening and directly registered
with the impeller housing of the jet pump in close proximity to its
impeller. It has been found that this causes pulsations in the
water that is transmitted back through the forward wall of the
bulkhead that separates the jet pump from the engine compartment
and can create unpleasant vibrations in the watercraft and sounds
that are undesirable.
[0005] It is, therefore, a first principal feature of this
invention to provide an improved and low cost jet propulsion unit
for a personal watercraft that avoids these pulsations.
[0006] It is a further object of this invention to provide an
arrangement for utilizing this feature in conjunction with
conventional type jet pumps so as to not require a redesign in
either the hull or the jet pump in order to use the feature of the
invention.
[0007] The copending application presents a solution to this
problem, but further improvements are desirable. It is therefore
another object of this invention to provide such further
improvements.
SUMMARY OF INVENTION
[0008] This invention is adapted to be embodied in a personal
watercraft that is comprised of a hull having an undersurface
including a vertically extending bulkhead defining in part a rear
portion of an engine compartment containing a prime mover. The hull
undersurface defines at least in part a downwardly facing water
inlet opening through which water may be drawn and a curved
discharged path that curves upwardly from said water inlet opening
toward the bulkhead. A support plate is fixed to the rear side of
the bulkhead. An extension housing is affixed to the support plate
at one end thereof. A jet propulsion system is carried by the other
end of the extension housing. The jet propulsion system is
comprised of an outer housing having an impeller portion, an
impeller rotatably journalled about an impeller axis in the
impeller portion and driven by the prime mover and a discharge
nozzle portion positioned rearwardly of the impeller though which
the water pumped by the impeller is discharged for propelling the
personal watercraft. The support plate and the extension housing
defining a water opening path leading in a direction parallel to
the impeller axis and having a shape that constitutes generally an
extension of the opening of an inlet to the impeller housing
portion so as to isolate the pulsations generated by the impeller.
The water opening path has a length greater than the axial length
of the impeller.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a side elevational view of a personal watercraft
constructed in accordance with an embodiment of the invention.
[0010] FIG. 2 is an enlarged broken away view showing the
construction of the jet pump arrangement of embodiment shown in
FIG. 1.
[0011] FIG. 3 is an enlarged front elevational view showing the
front or inlet face of the support plate for the jet propulsion
unit in accordance with this embodiment of the invention.
[0012] FIG. 4 is a cross sectional view taken along the line 4-4 of
FIG. 3 and shows the attached components.
[0013] FIG. 5 is a bottom plan view of the components shown in FIG.
2 and which comprise generally the underlying units of the jet
propulsion system.
[0014] FIG. 6 is a cross sectional view in part similar to FIG. 2,
but showing a further embodiment of the invention.
[0015] FIG. 7 is a further enlarged cross sectional view of a
portion of the structure shown in FIG. 6.
DETAILED DESCRIPTION
[0016] Referring in detail first to FIG. 1, a personal watercraft
constructed in accordance with an embodiment of the invention is
shown and identified generally by the reference numeral 11. It is
to be understood that, although the invention is described in
conjunction with a personal watercraft, certain of the features
herein disclosed may be utilized with other types of watercraft.
However, the invention has particular utility in conjunction with
personal watercraft due to their small size, compact nature and due
to the increased demand for providing quieter operating watercraft
of this type.
[0017] The watercraft 11 is comprised of a hull that consists
primarily of a hull under portion 12 and deck portion 13 that are
connected to each other along their peripheral edges by a gunnel
14. The deck portion 13 has longitudinally extending riders, area
on which a straddle type seat 15 on which the rider/operator and
two or three additional passengers may be seated. The seating is in
straddle, tandem position and the operator and his passengers place
their feet in foot wells disposed on opposites sides of the seat
15.
[0018] A control handlebar 16 is positioned forwardly of the seat
15 for operation by the rider/operator so as to steer the
watercraft, control it speed and other functions.
[0019] A prime mover such as an internal combustion engine, shown
schematically at 17 is contained in an engine compartment that is
formed within the hull under portion 12 and which may be accessible
through removal of the seat 15 and exposure of an access opening
formed in the raised part of the riders' area of the deck portion
13. This engine 17 drives a jet propulsion unit, indicated
generally by the reference numeral 18, positioned in a tunnel at
the rear of the hull under portion 12 in a manner, which will be
described now in connection with reference to FIGS. 1 through
5.
[0020] Referring now primarily to these figures, the hull under
portion 12 has a portion that defines a tunnel 19 in which the
conventional jet propulsion unit housing assembly is mounted. This
conventional part of unit includes the impeller housing portion 21
that contains the impeller 22, a discharge nozzle portion 23, a
steering nozzle 24 and a reverse thrust bucket 25. In FIG. 2, the
reverse thrust bucket 25 is shown in its opened or forward drive
condition.
[0021] In this embodiment, the impeller housing portion 21 is
disposed rearwardly from a bulkhead 26 formed by the hull under
portion 12 forwardly of the tunnel 19 and at the rear of the
compartment containing the engine 17 so as to accommodate a
silencing or extension and mounting assembly, indicated generally
by the reference numeral 27. This silencing extension assembly 27
will be described in more detail later by reference to FIGS. 2-5.
It is this silencing extension assembly 27 that is utilized, at
least in part, to secure the jet propulsion unit impeller housing
portion 21 and other attached components to the bulkhead 26.
[0022] In this assembly, a ride plate, indicated generally by the
reference numeral 28 and as seen in FIG. 5, is comprised of flanges
that receive threaded fasteners 29 for affixing it suitably to the
hull under portion 12.
[0023] It will be seen from FIG. 2 that forwardly of the bulkhead
26 the hull under portion 12 has a generally curved configuration
31 that defines a water inlet passage 32 that curves upwardly and
which registers with the silencing extension assembly 27 in manner
to be described. However, the generally curved configuration 31 is
formed with an indentation 33 which cooperates with a grill
assembly 34 that has a plurality of spaced grilled bars and
mounting portion 35 at its forward end. Threaded fasteners 36
connect this portion of the grill assembly 34 to a reinforcement
plate formed on the inner surface of the hull generally curved
configuration 31.
[0024] The rear end of the grill assembly 34 is received in a
recess 37 of an additional mounting plate 38 that is affixed to the
hull under portion 12 by threaded fasteners 39 and further
fasteners 41 that are connected to an extension piece of the
mounting plate 38 that defines the recess 37. It will be seen from
FIG. 3 that this then provides a fairly wide and elongated inlet
opening for the water inlet passage 32.
[0025] Referring now to the construction of the silencing extension
assembly 27, by reference primarily to FIGS. 2-4, it includes a
mounting flange portion, indicated generally by the reference
numeral 42. This flange portion 42 has lugs 43 that receive
threaded fasteners 44 for securing the mounting bracket to a
further mounting plate 45 that is fixed in a recess defined by the
bulkhead 26 and the mounting plate 38.
[0026] The mounting flange portion 42 further forms an annual
groove 46 in which an elastic sleeve 47 is positioned. Rearwardly
of this, the mounting flange portion 42 has a recess 48 that
receives an extension 49 of the impeller housing 14 (FIG. 4). This
construction provides a continuous water flow path through the
silencing extension assembly 27 best seen in FIG. 2). That is, the
silencing extension assembly 27 and the mounting plate 45 define a
continuous opening 51 extending rearwardly of the bulkhead 26. This
passageway is substantially the same diameter as that of the
portion 52 of the impeller housing 14 that surrounds the impeller
22. This has a length L5 which is comprised of the segment L4 which
comprises the length of the portion of the continuous opening 51 in
the mounting plate 45, the length L1 which is the combined length
of the mounting flange portion 42 and the elastic sleeve 47 and the
length L3 which comprises the remainder of the length downstream of
the elastic sleeve 47 and upstream of the impeller 22. The impeller
length L2 is approximately equal to about 50 mm while the length L5
is about 80 mm. In other words, the length L5 is substantially
greater than the length of the impeller 22 and in fact nearly
double that length. This provides very, very effective silencing
and isolation of pulsation damping in addition to the damping
effect caused by the elastic sleeve 47.
[0027] As shown in FIGS. 1 and 2 an impeller shaft 53 that extends
forwardly through the water inlet passage 32 for its coupling to
the output shaft of the engine 17 through a surrounding protective
sleeve (not shown).
[0028] FIGS. 6 and 7 show another embodiment of the invention,
which is similar in many regards to the embodiment thus far
described. Where the same components are employed, they have been
identified by the same reference numerals and will not be described
in more detail. This embodiment, however, permits greater latitude
in adjustment of the length of the various components leading up to
the impeller 22.
[0029] In this embodiment, a first mounting flange 101 is affixed
to the bulkhead 26 by means of threaded fasteners comprised of
studs 100 threaded into the mounting flange and nuts 102 received
thereon. This mounting flange 101 has a water flow opening 103 that
has substantially the same diameter as the remaining openings
leading up to the impeller 22 and the inner diameter 52 of the
impeller housing 21.
[0030] Affixed to this mounting flange 101 is a spacer flange 104
that is fixed to the mounting flange 101 by threaded fasteners 105.
The spacer flange 104 has a stepped opening 106 in which an
elastomeric sleeve 107 is received. It should be seen that this
sleeve 107 actually extends forwardly within a recess 108 of the
mounting flange 101 so that the elastic sleeve 107 can have a
greater length than the previously described embodiment. In this
embodiment the impeller housing 14 has an outer flange against
which the threaded fasteners 105 act to secure the impeller housing
14 to the spacer flange 104 and thus to the mounting flange 101 and
the bulkhead 26.
[0031] In addition, the rear portion of the spacer flange 104 is
provided with a recess 109 that receives an extending portion 111
of the impeller housing 14. This extending portion 111 backs up the
elastic sleeve 107 and holds it in place.
[0032] The impeller housing 14 is formed primarily from aluminum or
an aluminum alloy. Therefore a suitable lining material 112 such as
a stainless steel sleeve may be provided around the inner surface
of the impeller housing portion 14. This provides corrosion
protection and reduced cost. The lining sleeve 112 has an inner
diameter 113 that is the same as the flow opening 103 and the
elastic sleeve 107 and the diameter 52 of the impeller housing 21
Therefore, there is provided a flow length consisting of the
dimensions L1 and L3 provided by the mounting sleeve 104 and a part
of the impeller housing formed by the extension 111. This combined
length is substantially greater than the length L2 of the impeller
22. In this particular embodiment, these lengths are equal to
approximately 60 mm, which is greater than the length of the
impeller, which is 55 mm (L8). Of course, the length of the intake
passage 103 formed in the mounting rings 101 further adds to the
silencing effect.
[0033] These drawings further show how a nacelle and straightening
vane section 114 of the jet propulsion unit 18 is connected to the
impeller housing 21 by threaded fasteners 115. A tongue 116 of the
nacelle and straightening vane section 114 fits into a groove 117
in the rear of the impeller housing 21 for ease of assembly and
alignment. A similar tongue and groove arrangement is provided in
the connection at the rear of the nacelle and straightening vane
section 114 to the discharge nozzle section 23. The nacelle and
straightening vane section 114 has a flow diameter 118 that is the
same as those upstream flow diameters.
[0034] Thus, from the foregoing description is should be readily
apparent that the features of the invention provide a very
effective silencing for the jet propulsion unit for powering a
watercraft that is particularly adept for use in personal
watercraft. It is to be understood, however, that the foregoing
description is that of preferred embodiments of the invention and
various changes and modifications may be made without departing
from the spirit and scope of the invention, as defined by the
appended claims.
* * * * *