U.S. patent application number 10/667165 was filed with the patent office on 2004-03-25 for reverse gate for water jet propulsion system.
Invention is credited to Westhoff, Paul E..
Application Number | 20040058596 10/667165 |
Document ID | / |
Family ID | 29586558 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058596 |
Kind Code |
A1 |
Westhoff, Paul E. |
March 25, 2004 |
Reverse gate for water jet propulsion system
Abstract
A non-steerable reverse gate having a structure which reverses
the lateral flow component when the steering nozzle is turned. The
reverse gate produces high reverse and steering thrusts, while
requiring low operating loads. The steering response in reverse is
the same as an outboard or inboard/outboard. In effect, the transom
thrusts to the side that the steering wheel is turned to. The
reverse gate has a pair of flow-reversing passages for providing
reverse thrust, a lateral steering passage for producing a lateral
thrust when the steering nozzle is turned, and a fixed or pivotable
central deflector body. The deflector body has three vertical walls
connected to a juncture. One vertical wall is straight and extends
forward of the juncture. The other vertical walls are curved and
extend rearward and laterally outward from the juncture on opposite
sides of a plane of symmetry. Each curved vertical wall has a
flow-deflecting surface which is concave and faces a front opening
of the reverse gate. The straight vertical wall splits the incoming
flow into two streams, while the flow-deflecting surfaces divert
portions of the respective streams toward the respective
flow-reversing passages. Steering in reverse is provided by water
which flow around the deflector body and out a discharge opening of
the lateral steering passage.
Inventors: |
Westhoff, Paul E.; (Kenosha,
WI) |
Correspondence
Address: |
ZIOLKOWSKI PATENT SOLUTIONS GROUP, LLC (BRPI)
14135 NORTH CEDARBURG ROAD
MEQUON
WI
53097-1416
US
|
Family ID: |
29586558 |
Appl. No.: |
10/667165 |
Filed: |
September 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10667165 |
Sep 17, 2003 |
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10319433 |
Dec 13, 2002 |
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6652332 |
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60339684 |
Dec 13, 2001 |
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Current U.S.
Class: |
440/41 |
Current CPC
Class: |
B63H 11/11 20130101 |
Class at
Publication: |
440/041 |
International
Class: |
B63H 011/11 |
Claims
1. A reverse gate comprising: a housing having a front opening and
comprising first and second flow-reversing passages arranged on
opposing sides thereof, each of said first and second
flow-reversing passages having an inlet and a discharge opening,
and a lateral steering passage located in a rear portion of said
housing, said lateral steering passage having discharge openings at
opposite ends thereof; and a deflector body arranged inside said
housing, said deflector body comprising a straight vertical wall
and first and second curved vertical walls, each of said vertical
walls being connected to a juncture, said straight vertical wall
extending forward from said juncture, and said first and second
curved vertical walls extending rearward and laterally outward from
said junction, said first and second curved vertical walls
extending along arcs on opposite sides of a plane which is
generally co-planar with said straight vertical wall, the concave
sides of said curved vertical walls generally facing said front
opening and the convex sides of said curved vertical walls
generally facing said lateral steering passage.
2. The reverse gate as recited in claim 1, wherein said deflector
body is pivotably mounted to said housing.
3. The reverse gate as recited in claim 2, further comprising a
pair of pivot pins coupled to said straight vertical wall for
pivotably mounting said deflector body to said housing.
4. The reverse gate as recited in claim 2, wherein said deflector
body pivots freely over a predetermined range of angles.
5. The reverse gate as recited in claim 1, wherein said straight
vertical wall and said first curved vertical wall form a J
shape.
6. The reverse gate as recited in claim 1, wherein said first and
second curved vertical walls have shapes which mirror each
other.
7. The reverse gate as recited in claim 1, wherein said housing
comprises top and bottom walls connected by first and second curved
outer walls on opposing sides thereof, forward portions of said
first and second curved outer walls forming portions of said first
and second flow-reversing passages respectively, and rear portions
of said first and second curved outer walls partly forming said
discharge openings of said lateral steering passage.
8. The reverse gate as recited in claim 7, wherein said first and
second curved vertical walls have distal ends which do not contact
said first and second curved outer walls respectively.
9. A reverse gate comprising: a housing having a front opening and
comprising first and second flow-reversing passages arranged on
opposing sides thereof, each of said first and second
flow-reversing passages having an inlet and a discharge opening,
and a lateral steering passage located in a rear portion of said
housing, said lateral steering passage having discharge openings at
opposite ends thereof; and a deflector body arranged inside said
housing, said deflector body comprising first and second vertical
surfaces, said first vertical surface extending straight from a
first point adjacent said front opening to a second point located
rearward of said first point and then curving along a first arc
from said second point to a third point, and said second vertical
surface extending straight from a fourth point adjacent said front
opening to a fifth point located rearward of said fourth point and
then curving along a second arc from said fifth point to a sixth
point, wherein said first and fourth points are separated by a
thickness of a leading edge of said deflector body, said first and
second arcs are equal to each other, and said third and sixth
points are symmetrically located on opposing sides of a plane of
symmetry defined by a plane midway between said straight portions
of said first and second vertical surfaces.
10. The reverse gate as recited in claim 9, wherein the transitions
from said straight portions to said curved portions at said second
and fifth points are smooth.
11. The reverse gate as recited in claim 9, wherein said first and
second arcs are each greater than 90 degrees.
12. The reverse gate as recited in claim 9, wherein said deflector
body is pivotably mounted to said housing.
13. The reverse gate as recited in claim 12, further comprising a
pair of pivot pins coupled to said deflector body along a section
having said straight portions on opposing sides thereof.
14. The reverse gate as recited in claim 12, wherein said deflector
body pivots freely over a predetermined range of angles.
15. The reverse gate as recited in claim 9, wherein each of said
first and second vertical surfaces forms a J shape.
16. The reverse gate as recited in claim 9, wherein said housing
comprises top and bottom walls connected by first and second curved
outer walls on opposing sides thereof, forward portions of said
first and second curved outer walls forming portions of said first
and second flow-reversing passages respectively, and rear portions
of said first and second curved outer walls partly forming said
discharge openings of said lateral steering passage.
17. The reverse gate as recited in claim 9, wherein a distal end of
said curved portion of said first vertical surface is directed
toward said inlet of said first flow-reversing passage, and a
distal end of said curved portion of said second vertical surface
is directed toward said inlet of said second flow-reversing
passage.
18. A water jet propulsion system comprising: a duct having an
inlet and an outlet; an impeller which is rotatable within said
duct; a steering nozzle pivotably mounted to an outlet end of said
duct and having an inlet and an outlet, said steering nozzle being
pivotable between first and second steering positions, and said
steering nozzle inlet being in flow communication with said duct
outlet; and a reverse gate pivotably mounted to said duct, said
reverse gate being pivotable about a pivot axis between first and
second shift positions, said reverse gate in said first shift
position being removed from the path of water exiting said steering
nozzle outlet and in said second shift position being in the path
of water exiting said steering nozzle outlet, wherein said reverse
gate comprises: a housing having a front opening which faces said
steering nozzle outlet when said reverse gate is in said second
shift position, said housing comprising first and second
flow-reversing passages arranged on opposing sides thereof, each of
said first and second flow-reversing passages having an inlet and a
discharge opening, and a lateral steering passage located in an aft
portion of said housing, said lateral steering passage having
discharge openings at opposite ends thereof; and a deflector body
arranged inside said housing, said deflector body comprising a
straight vertical wall and first and second curved vertical walls,
each of said vertical walls being connected to a juncture, said
straight vertical wall extending forward from said juncture, and
said first and second curved vertical walls extending rearward and
laterally outward from said junction, said first and second curved
vertical walls extending along arcs on opposite sides of a plane
which is generally co-planar with said straight vertical wall, the
concave sides of said curved vertical walls generally facing said
front opening and the convex sides of said curved vertical walls
generally facing said lateral steering passage.
19. The water jet propulsion system as recited in claim 18, wherein
said deflector body is pivotably mounted to said housing.
20. The water jet propulsion system as recited in claim 19, wherein
said deflector body pivots freely over a predetermined range of
angles.
21. The water jet propulsion system as recited in claim 18, wherein
said housing comprises top and bottom walls connected by first and
second curved outer walls on opposing sides thereof, forward
portions of said first and second curved outer walls forming
portions of said first and second flow-reversing passages
respectively, and rear portions of said first and second curved
outer walls partly forming said discharge openings of said lateral
steering passage.
22. A water jet propulsion system comprising: a duct having an
inlet and an outlet; an impeller which is rotatable within said
duct; a steering nozzle pivotably mounted to an outlet end of said
duct and having an inlet and an outlet, said steering nozzle being
pivotable between first and second steering positions, and said
steering nozzle inlet being in flow communication with said duct
outlet; and a reverse gate pivotably mounted to said duct, said
reverse gate being pivotable about a pivot axis between first and
second shift positions, said reverse gate in said first shift
position being removed from the path of water exiting said steering
nozzle outlet and in said second shift position being in the path
of water exiting said steering nozzle outlet, wherein said reverse
gate comprises: a housing having a front opening which faces said
steering nozzle outlet when said reverse gate is in said second
shift position, said housing comprising first and second
flow-reversing passages arranged on opposing sides thereof, each of
said first and second flow-reversing passages having an inlet and a
discharge opening, and a lateral steering passage located in an aft
portion of said housing, said lateral steering passage having
discharge openings at opposite ends thereof; and a deflector body
pivotably mounted inside said housing.
23. The water jet propulsion system as recited in claim 22, wherein
said deflector body pivots freely over a predetermined range of
angles.
24. The water jet propulsion system as recited in claim 22, wherein
said deflector body comprises a straight vertical wall and first
and second curved vertical walls, each of said vertical walls being
connected to a juncture, said straight vertical wall extending
forward from said juncture, and said first and second curved
vertical walls extending rearward and laterally outward from said
junction, said first and second curved vertical walls extending
along arcs on opposite sides of a plane which is generally
co-planar with said straight vertical wall, the concave sides of
said curved vertical walls generally facing said front opening and
the convex sides of said curved vertical walls generally facing
said lateral steering passage.
25. The water jet propulsion system as recited in claim 22, wherein
said deflector body comprises first and second vertical surfaces,
said first vertical surface extending straight from a first point
adjacent said front opening to a second point located rearward of
said first point and then curving along a first arc from said
second point to a third point, and said second vertical surface
extending straight from a fourth point adjacent said front opening
to a fifth point located rearward of said fourth point and then
curving along a second arc from said fifth point to a sixth point,
wherein said first and fourth points are separated by a thickness
of a leading edge of said deflector body, said first and second
arcs are equal to each other, and said third and sixth points are
symmetrically located on opposing sides of a plane of symmetry
defined by a plane midway between said straight portions of said
first and second vertical surfaces.
26. A water jet propulsion system comprising: a duct having an
inlet and an outlet; an impeller which is rotatable within said
duct; a steering nozzle pivotably mounted to an outlet end of said
duct and having an inlet and an outlet, said steering nozzle being
pivotable between first and second steering positions, and said
steering nozzle inlet being in flow communication with said duct
outlet; and a reverse gate pivotably mounted to said duct, said
reverse gate being pivotable about a pivot axis between first and
second shift positions, said reverse gate in said first shift
position being removed from the path of water exiting said steering
nozzle outlet and in said second shift position being in the path
of water exiting said steering nozzle outlet, wherein said reverse
gate comprises: a housing having a front opening which faces said
steering nozzle outlet when said reverse gate is in said second
shift position, said housing comprising first and second
flow-reversing passages arranged on opposing sides thereof, each of
said first and second flow-reversing passages having an inlet and a
discharge opening, and a lateral steering passage located in an aft
portion of said housing, said lateral steering passage having
discharge openings at opposite ends thereof; and a deflector body
mounted inside said housing, said deflector body comprising first
and second vertical surfaces, said first vertical surface extending
straight from a first point adjacent said front opening to a second
point located rearward of said first point and then curving along a
first arc from said second point to a third point, and said second
vertical surface extending straight from a fourth point adjacent
said front opening to a fifth point located rearward of said fourth
point and then curving along a second arc from said fifth point to
a sixth point, wherein said first and fourth points are separated
by a thickness of a leading edge of said deflector body, said first
and second arcs are equal to each other, and said third and sixth
points are symmetrically located on opposing sides of a plane of
symmetry defined by a plane midway between said straight portions
of said first and second vertical surfaces.
Description
FIELD OF THE INVENTION
[0001] This invention generally relates to water jet apparatus for
propelling boats and other watercraft. In particular, the invention
relates to mechanisms for shifting a water jet apparatus to
selectively propel a craft in the forward or reverse direction.
BACKGROUND OF THE INVENTION
[0002] It is known to propel a boat or other watercraft using a
water jet apparatus mounted to the hull, with the powerhead being
placed inside (inboard) the hull. An impeller is mounted on a shaft
driven by a drive shaft of the motor, and is housed in a duct
having an inlet and an outlet. The impeller is designed such that
during motor operation, the rotating impeller impels water rearward
through the duct. The water discharged from the duct outlet
produces a thrust which propels the boat forward.
[0003] In addition, it is known to provide a mechanism for
diverting the discharged water flow to one side or the other of a
midplane, thereby enabling the boat operator to steer the boat to
the left or right during forward propulsion. One such mechanism is
a steering nozzle pivotably mounted to the duct and in flow
communication with the duct outlet. Preferably the pivot axis of
the steering nozzle lies in the midplane. As the steering nozzle is
pivoted to the left of a central position, the water flow out of
the duct is diverted leftward, producing a thrust which pushes the
water jet apparatus and the boat stern to the right, thereby
causing the bow of the boat to turn to the left. Similarly, the
boat bow turns to the right when the steering nozzle is pivoted to
the right of the central position.
[0004] It is also known to provide a mechanism for reversing the
direction of the water flow exiting the steering nozzle. The
reverse gate can be pivotably mounted to the steering nozzle, its
pivot axis being generally perpendicular to the pivot axis of the
steering nozzle. In the up position, the reverse gate is clear of
the water flow exiting the steering nozzle. In the down position,
the reverse gate is disposed in the path of the exiting water flow.
In its simplest embodiment, the reverse gate has a U-shaped channel
which reverses the water flow exiting the steering nozzle. In other
words, when the steering nozzle is turned to the left, the
resulting water flow having rearward and leftward flow components
is redirected by the reverse gate to have forward and rightward
components. This produces a thrust which pulls the boat rearward
and propels the water jet apparatus and boat stern to the left,
causing the boat to turn left during rearward movement. Similarly,
the boat turns to the right during rearward movement when the
steering nozzle is turned to the right. The provision of a
steerable reverse gate allows the boat operator to steer in forward
and reverse in the same manner that an automobile can be
steered.
[0005] In accordance with other known designs, the reverse gate is
not steerable, i.e., the reverse gate is pivotably mounted to the
water jet housing. In the up position, the reverse gate is clear of
the water flow exiting the steering nozzle; in the down position,
the reverse gate obstructs the water flow exiting the steering
nozzle and reverses the rearward flow component. Some non-steerable
designs also reverse the lateral flow component; others do not. The
non-steerable reverse gate designs which reverse the lateral flow
component cause the rearward-moving boat to turn left when the
steering nozzle is turned to the left and to turn right when the
steering nozzle is turned to the right. However, these prior
designs provide less than optimal reverse thrust and steering
thrust. There is a need for a non-steerable reverse gate which
reverses the lateral flow component, provides increased reverse and
steering thrusts, and operates with low cable loads.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a non-steerable reverse
gate having a structure which reverses the lateral flow component
when the steering nozzle is turned. The reverse gates in accordance
with the preferred embodiments produce high reverse and steering
thrusts, while requiring low operating loads. The steering response
in reverse is the same as an outboard or inboard/outboard. In
effect, the transom thrusts to the side that the steering wheel is
turned to. The invention is also directed to a water jet propulsion
system having a non-steerable reverse gate of the foregoing
type.
[0007] In accordance with one preferred embodiment of the
invention, the reverse gate comprises a pair of flow-reversing
passages for providing reverse thrust, a lateral steering passage
for producing a lateral thrust when the steering nozzle is turned,
and a fixed central deflector body. In accordance with another
preferred embodiment, the central deflector body is pivotable about
a vertical axis.
[0008] In accordance with both preferred embodiments disclosed
herein, the flow-reversing passages are located on opposite (i.e.,
port and starboard) sides of the reverse gate. Each flow-reversing
passage has an inlet and an outlet. The lateral steering passage is
located aft of the deflector body and reversing passages and has
discharge openings on opposite ends thereof, i.e., on the port and
starboard sides of the reverse gate. The lateral steering passage
communicates with the main chamber of the reverse gate via an
aperture which is centered between port and starboard curved outer
walls of the reverse gate. These port and starboard curved outer
walls extend forward and laterally outward to form the outer side
walls of the flow-reversing passages. The central aperture allows
some of the water discharged from the steering nozzle to enter the
lateral steering passage. The deflector is situated in front of the
aperture to deflect some of the pump discharge to the sides and
into the flow-reversing passages.
[0009] The deflector body in accordance with the first preferred
embodiment of the invention comprises three vertical walls
connected at a central vertical line located midway between the
reversing passage inlets. The three vertical walls are preferably
attached or joined to the top and bottom walls of the reverse gate
housing. One vertical wall of the deflector body lies in the
reverse gate midplane and extends forward from the central juncture
of the walls. The other vertical walls of the deflector body are
laterally curved in the shape of respective arcs. One arc curves
from the central juncture toward the inlet of the reversing passage
on the port side of the reverse gate; the other arc curves from the
central juncture toward the inlet of the reversing passage on the
starboard side of the reverse gate. These curved vertical walls
will be referred to herein as flow-deflecting walls. The concave
side of each flow-deflecting wall faces toward a wide opening in
the front of the reverse gate, through which the water discharged
from the steering nozzle outlet flows into the reverse gate. The
flow-deflecting walls respectively guide or deflect incoming water
toward the respective inlets of the opposing reversing passages.
The incoming stream of water is split by the central vertical wall
into two streams which respectively flow along the front surfaces
of the curved vertical walls. In accordance with the preferred
embodiment, the port surface of the central vertical wall and the
front surface of the curved vertical wall on the port side form a
continuous surface having a J-shaped contour which redirects one
stream of incoming water toward the port reversing passage;
similarly, the starboard surface of the central vertical wall and
the front surface of the curved vertical wall on the starboard side
form a continuous surface having a J-shaped contour which redirects
the other stream of incoming water toward the starboard reversing
passage.
[0010] In accordance with the first preferred embodiment, each
curved vertical wall terminates at a sufficient distance from the
opposing curved outer wall and each curved outer wall is suitably
oriented, so that some water discharged from a steering nozzle
steered to one side is directed by the curved outer wall on that
side through the aperture and out the discharge opening on the
opposite side of the lateral steering passage. Water which flows
around the port curved vertical wall of the deflector body is
directed to the starboard discharge opening of the lateral steering
passage; while water which flows around the port curved vertical
wall of the deflector body is directed to the starboard discharge
opening of the lateral steering passage.
[0011] The deflector body in accordance with the second preferred
embodiment has a shape similar to that of the first embodiment
described above, i.e., three vertical walls connected at a vertical
juncture to form back-to-back J shapes having a common spine. The
deflector body of the second preferred embodiment differs from the
deflector body of the first preferred embodiment in two respects:
(1) the former is pivotable about a vertical axis, whereas the
latter is fixed; and (2) the lateral span from the end of the port
curved vertical wall to the end of the starboard curved vertical
wall of the former is greater than the corresponding span of the
latter. These differences are related in that the ability of the
deflector body to pivot in either direction makes it possible to
extend the length of the curved vertical walls without decreasing
the gap between the end of the curved vertical wall and the curved
outer wall on the opposite side. The longer laterally curved
vertical walls of the deflector body increase the angle by which
the incoming water is turned, direct more water into the
flow-reversing passages. This increases reversing thrust
significantly without diminishing the steering thrust.
[0012] For embodiments wherein the deflector body pivots about a
vertical axis passing through the central vertical wall, the
central vertical wall will be referred to as a leading rudder. When
the steering nozzle is centered, the steering nozzle discharge is
split by the leading rudder. The respective streams are then
diverted into the respective flow-reversing passages by the
respective flow-deflecting walls of the deflector body. Steering,
i.e., turning the steering nozzle about its pivot axis, in one
direction applies unequal forces on the two sides of the deflector
body, causing it to pivot in the opposite direction. This allows
some of the nozzle discharge on the other side of the leading
rudder to miss the deflector body, escape around the backside, and
then flow through the aperture behind the deflector body, into the
lateral steering passage, and out the steering passage discharge
opening on the same side toward which the deflector body has been
turned. This design produces high steering thrust during flow
reversal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic (presented in two sheets respectively
labeled FIGS. 1A and 1B) showing a sectional view of a known water
jet propulsion system mounted to a boat hull, the section being
taken along a vertical midplane.
[0014] FIG. 2 is a schematic (presented in two sheets respectively
labeled FIGS. 2A and 2B) showing a top view of the top mounting
plate and the water jet apparatus depicted in FIG. 1, with the hull
removed.
[0015] FIG. 3 is a schematic showing a sectional view of the shift
and steering control housing shown in FIG. 2A, the section being
taken along line 3-3 in FIG. 2A.
[0016] FIG. 4 is a schematic showing an isometric view of a reverse
gate having a fixed deflector body in accordance with one preferred
embodiment of the invention.
[0017] FIG. 5 is a schematic showing a front elevational view of
the reverse gate depicted in FIG. 4.
[0018] FIG. 6 is a schematic showing a plan view of the reverse
gate depicted in FIGS. 4 and 5. The fixed deflector body is
indicated by dashed lines.
[0019] FIG. 7 is a schematic showing a front elevational view of a
reverse gate having a pivotable deflector body in accordance with
another preferred embodiment of the invention.
[0020] FIGS. 8 and 9 are schematics showing plan views of the
reverse gate depicted in FIG. 7, with the deflector body in a
central position (FIG. 8) and pivoted to starboard (FIG. 9).
[0021] FIG. 10 is a schematic showing a plan view of the reverse
gate in accordance with the second preferred embodiment mounted to
a water jet propulsion system (only partly shown).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] FIGS. 1 and 2 depict a prior water jet propulsion system
which incorporates a steering nozzle and a reverse gate. These
drawings show a basic structure for such a system, as well as one
possible means for controlling the rotational positions of the
steering nozzle and the reverse gate. The reverse gate shown in
FIGS. 1B and 2B is not part of the present invention. The reverse
gate in accordance with the preferred embodiments of the invention
will be described in detail later with reference to FIGS. 4-10.
FIGS. 1-3 are presented for the purpose of disclosing exemplary
mechanisms for enabling a boat operator to remotely control the
positions of a steering nozzle and reverse gate. However, it should
be appreciated that the reverse gate of the invention can be
utilized in water jet propulsion apparatus different in structure
than that shown in FIGS. 1 and 2.
[0023] The water jet propulsion apparatus shown in FIG. 1 is
designed to be installed in a cavity under a section of the hull
and in flow communication with the outlet of an inlet ramp built
into the hull. As seen in FIG. 1, the boat hull 2 has a inlet ramp
6 formed by a pair of opposing sidewalls 8 (only one of which is
visible in FIG. 1) and a guide surface or ceiling 10 which curves
gently upward in the aft direction. The end of the inlet ramp 6
communicates with a cavity in which the water jet propulsion
apparatus is installed. This cavity is defined by a horizontal hull
section 12, a vertical hull section 14 and a pair of opposing
sidewalls 16 (only one of which is visible in FIG. 1), the cavity
being open at the bottom and rear to allow insertion of the water
jet propulsion apparatus.
[0024] The apparatus depicted in FIG. 1 comprises an inlet housing
18, which is slid into the aforementioned cavity and bolted to the
hull by means of a top mounting plate 20 and a front plate 22. At
the time of inlet housing installation, the drive shaft 26 is
already rotatably mounted in the inlet housing. In particular, the
inlet housing 18 comprises a vertical strut 85 having an axial bore
which houses a portion of the drive shaft.
[0025] During inlet housing installation, the front plate 22 is
placed on the inside of the vertical hull section 14 and the inlet
housing 18 is placed on the outside of vertical hull section 14.
Screws 24 (only one of which is visible in FIG. 1) hold the front
plate, vertical hull section and inlet housing together. The front
plate 22 has an opening 34 (best seen in FIG. 2) which, in the
assembled state, is aligned with an opening 36 in the vertical hull
section 14 to allow the output shaft (not shown) from the inboard
motor to be coupled to the front end of the drive shaft 26. The
studs 28 are affixed to the inlet housing 18. The inlet housing 18
is inserted into the hull cavity and the studs 28 are inserted into
throughholes in the hull. The front plate 22 is then positioned and
screws 24 are screwed into the inlet housing 18. The top mounting
plate 20 is then placed over the studs 28 and secured to the hull.
The top mounting plate 20 has an opening 38 which, in the assembled
state, is aligned with an opening 40 in the horizontal hull section
12 to allow a shift and steering control housing 42 to be placed in
a corresponding opening in the top wall of the inlet housing
18.
[0026] The inlet housing 18 has a water tunnel 44 with an inlet 46.
The water tunnel 44 comprises a pair of sidewalls 48 (only one of
which is shown in FIG. 1) which are generally coplanar with the
sidewalls 8 of the hull inlet ramp 6. In addition, water tunnel 44
comprises a guide surface 50 which starts at a point near where the
guide surface 10 of the hull inlet ramp 6 ends and then curves
gradually upward in the aft direction. The hull 2 and the inlet
housing 18 combine to form a single inlet for guiding water toward
the inlet of a stator housing 52 located downstream of the inlet
housing. An inlet grate 54, comprising a multiplicity of generally
parallel tines 56, extends across the inlet 46 to prevent debris
from entering. In addition, a ride plate 58 is attached to the
bottom of the inlet housing 18.
[0027] As shown in FIG. 1, the drive shaft projects in the aft
direction out of the inlet housing 18. The impeller is
pre-assembled in the unit prior to mounting in the hull. The hub
and blades of impeller 60 are preferably integrally formed as one
cast piece. The hub of impeller 60 has a splined bore which meshes
with splines formed on the external surface of the drive shaft 26,
so that the impeller 60 will rotate in unison with the drive shaft.
The impeller 60 is held on a threaded end of the drive shaft 26 by
a threaded nut 64.
[0028] The stator housing 52 comprises inner and outer shells
connected by a plurality of stator vanes, all integrally formed as
a single cast piece. The stator vanes are designed to redirect the
swirling flow out of the impeller 60 into non-swirling flow. A tail
cone cover 66 is attached to the radial end face of the stator
housing hub. The front of the stator housing 52 is then attached to
the rear of the inlet housing 18. A circumferential recess in the
stator housing 52 at a position opposing the impeller blade tips
has a circular cylindrical wear ring 65 seated therein.
[0029] An exit nozzle 70 is attached to and in flow communication
with the stator housing 52. Water from the stator housing 52 flows
through the space between the tail cone cover 66 and the exit
nozzle 70. A steering nozzle 72 is pivotably mounted to the exit
nozzle 70 by a pair of pivot assemblies 74 and 76 having collinear
axes. The steering nozzle 72 can be turned to change the direction
of the water being discharged from the exit nozzle 70.
[0030] As best seen in FIG. 2B, the steering nozzle 72 has an arm
68 which is pivotably coupled to a flattened end of a steering rod
114. Displacement of the steering rod 114 in response to operation
of a steering cable assembly 78 (see FIG. 2A) causes the steering
nozzle 72 to swing in a desired direction about its vertical pivot
axis.
[0031] The water jet apparatus shown in FIGS. 1 and 2 is provided
with a non-steerable reverse gate 80, best seen in FIG. 2B. In the
forward position, the reverse gate 80 is raised, thereby allowing
water to exit the steering nozzle 72 freely. In the reverse
position, the reverse gate 80 is lowered to a position directly
opposite to the outlet of the steering nozzle 72. The reverse gate
is designed to partially reverse the flow of water exiting the
steering nozzle 72 when the reverse gate is in the reverse
position. To accomplish the foregoing, the arms 98 and 100 of the
reverse gate 80 are pivotably mounted to a pair of pivot assemblies
94 and 96 located on opposite sides of the exit nozzle 70 (see FIG.
2B). The support arms 98 and 100 are rigid members which connect to
the exit nozzle 70. The reverse gate 80 is pivoted by a shift rod
92, the end of which is coupled to arm 98 of the reverse gate 80 by
means of a rod end assembly 102 which comprises a ball socket for
allowing horizontal radial motion at the shift lever and vertical
radial motion at the reverse gate. The rod end assembly is attached
to arm 98 by means of a screw 104 and a lock nut 106. Displacement
of the shift rod 92 in response to operation of a shift cable
assembly 82 (see FIG. 2A) causes the reverse gate to swing in a
desired direction, namely, into forward position or reverse
position, with a "neutral" position therebetween.
[0032] In the apparatus depicted in FIGS. 1 and 2, the shift and
steering cable assemblies (located inside the hull) are
respectively coupled to shift and steering rods (located outside
the hull) by means of respective lever and shaft assemblies
rotatably supported in a shift and steering control housing 42
which penetrates the hull. The shift and steering control housing
42 is installed in a corresponding opening in the top of the inlet
housing 18. As seen in FIG. 2A, the housing 42 preferably comprises
a base plate 116; as best seen in FIG. 3, the housing 42 further
comprises an upper vertical tubular structures 118 and 120
extending above the base plate to different heights. The tubular
structures 118 and 120 are reinforced by a rib 122. Additional
reinforcement is provided by respective pairs of ribs visible in
FIG. 2A. Referring again to FIG. 3, below the base plate 116, the
housing has a circular cylindrical lower wall 128 integrally formed
with lower vertical tubular structures 130 and 132. The lower wall
128 slides into a circular opening formed in the top wall of the
inlet housing 18. The opening in the inlet housing communicates
with the exterior of the water jet apparatus via a pair of opposing
side channels through which the lower shift and steering levers
(described below) respectively pass. Preferably the opening 40 (see
FIG. 1A) in the horizontal hull section 12 closely matches the
opening in mounting plate. As seen in FIG. 2A, the housing 42 is
bolted to the inlet housing 18.
[0033] As seen in FIG. 3, the shift and steering control housing 42
has one bore 146 for receiving the shift shaft 88 and another bore
148 for receiving the steering shaft 110. The bore 146 has upper
and lower annular recesses in which upper and lower bushings 150
and 152 are respectively inserted; the bore 148 has upper and lower
annular recesses in which upper and lower bushings 154 and 156 are
respectively inserted. The shift shaft 88 is rotatably supported in
bushings 150 and 152, while steering shaft 110 is rotatably
supported in bushings 154 and 156. One end of the upper shift lever
86 is secured to the top of the shift shaft 88 by means of a lock
nut 158 which screws onto a threaded end of the shift shaft; one
end of the upper steering lever 108 is secured to the top of the
steering shaft 110 by means of a lock nut 160 which screws onto a
threaded end of the steering shaft. (Only a portion of each of the
upper levers is shown in FIG. 3.) The upper levers bear on the
flanges of the upper bushings during rotation of the lever and
shaft assemblies.
[0034] Still referring to FIG. 3, a lower shift lever 90 is welded
to the bottom of the shift shaft 88, while a lower steering lever
112 is welded to the bottom of the steering shaft 110. A lower
washer 178 is installed between the lower shift lever 90 and the
lower vertical tubular structure 130 of the shift and steering
control housing 42, while a lower washer 180 is installed between
the lower steering lever 112 and the lower vertical tubular
structure 132 of housing 42. The washers 178 and 180 provide a
bearing surface. During assembly, the bottoms of the shafts are
supported by a boss 138. The full length of the lower steering
lever 112 is shown in FIG. 3, while only a portion of the lower
shift lever 90 is depicted. FIG. 3 shows a clevis 182 and a
shoulder screw 184 for attaching the distal end of the lower
steering lever 112 to the forward end of the steering rod (not
shown in FIG. 3). Similarly, the distal end of the lower shift
lever is attached to the forward end of the shift rod by means of a
clevis and shoulder screw coupling (not shown in FIG. 3).
[0035] Referring to FIG. 2A, the distal end of the upper shift
lever 86 is attached to the shift cable assembly 82 by means of a
clevis 186 and a clevis pin 188. These components are located
inside the hull of the boat (see FIG. 1A). Displacement of the end
of the shift cable assembly causes the shift lever and shaft
assembly to rotate. Likewise the distal end of the upper steering
lever 108 is attached to the steering cable assembly 78 by means of
a clevis 190 and a clevis pin 192, and displacement of the end of
the steering cable assembly causes the steering lever and shaft
assembly to rotate. As best seen in FIG. 1A, the shift cable
assembly 82 is supported by a bracket 194 and the steering cable
assembly 78 is supported by a bracket 196, both brackets being
integrally connected to and extending vertically upward from the
top mounting plate 20. In response to operation of the steering
cable assembly 78, the steering nozzle can be selectively turned
left or right to steer the boat as desired during water jet
operation. In response to operation of the shift cable assembly 82,
the reverse gate can be selectively raised or lowered.
[0036] In accordance with the preferred embodiments of the
invention, the reverse gate is pivotably mounted to an exit nozzle
or to an integral stator housing/exit nozzle, and is pivotable
between first and second shift positions. The reverse gate in the
first shift position is removed from the path of water exiting the
exit nozzle and in the second shift position is disposed in the
path of water exiting the exit nozzle. Reverse gates in accordance
with first and second preferred embodiments of the invention are
shown in FIGS. 4-6 and in FIGS. 7-10 respectively, with the pivot
pin assemblies and the shift rod assembly for deploying the reverse
gate not shown. As seen in those drawings, the housings for the two
embodiments are substantially the same, while the major difference
between the embodiments lies in the deflector body, which is fixed
in the first embodiment and freely pivotable between limit stops in
the second embodiment. Although not shown in the drawings, the
invention also encompasses coupling the pivotable deflector body to
the steering nozzle or to the means for turning the steering
nozzle. The deflector body would be coupled to pivot in a direction
opposite to the direction in which the steering nozzle was
pivoted.
[0037] As seen in FIG. 4, pivot pins for pivotably supporting the
reverse gate would be received in coaxial pivot holes 196 and 196'
formed in mounting walls 198 and 198' respectively. The pivot pins
197 are shown in FIG. 10. The centerlines of the pivot pins 197
define the pivot axis. The reverse gate is deployed by actuating
the previously described shifting rod (92 in FIG. 2B), which is
coupled to the clevis 244 mounted to the top wall 210 of the
reverse gate. The fully down position of the reverse gate is shown
in FIG. 10. Preferably, the reverse gate is pivotably coupled to
the ends of a pair of support arms 200 and 200' which extend from
an integral stator housing/exit nozzle 202. The steering nozzle 204
is pivotably mounted to the exit nozzle by means of pivot pins 205,
one of which is visible in FIG. 10. The reverse gate must be shaped
to provide clearance between it and the steering nozzle during
deployment.
[0038] The reverse gates shown in FIGS. 4-10 each comprise port and
starboard flow-reversing passages 206 and 206' having respective
discharge openings 208 and 208'. As seen in FIGS. 5 and 7, the
distal sections of the flow-reversing passages 206 and 206' are
splayed downward and outward. Each of the flow-reversing passages
206 and 206' may have a generally rectangular cross section with
sharp or rounded corners. In particular, the flow-reversing
passages 206 and 206' are defined by respective portions of the top
wall 210, respective portions of the bottom wall 212, respective
portions of the port and starboard curved outer walls 214 and 214',
and the port and starboard inner side walls 216 and 216'
respectively.
[0039] In accordance with the preferred embodiments of the
invention, the reverse gate further comprises a lateral steering
passage 218 for producing a lateral thrust when the steering nozzle
is turned. As best seen in FIGS. 6 and 8, the lateral steering
passage 218 is located aft of the deflector body and reversing
passages and has discharge openings 220 and 220' on opposite ends
thereof, i.e., on the port and starboard sides of the reverse gate.
The lateral steering passage 218 comprises an aft wall 222 which is
laterally straight and aft portions of the top wall 210 and the
bottom wall 212. The discharge openings 220 and 220' are defined by
edges of the same walls in conjunction with respective portions of
the curved outer walls 214 and 214', as seen in FIGS. 6 and 8. The
lateral steering passage 218 communicates with the main chamber of
the reverse gate via an aperture 224 which is centered between port
and starboard curved outer walls 214 and 214' of the reverse gate.
The curved outer walls 214 and 214' extend forward and laterally
outward to form the outer side walls of the flow-reversing passages
206 and 206', respectively. The central aperture 224 allows some of
the water discharged from the steering nozzle to enter the lateral
steering passage 218.
[0040] As seen in FIGS. 5 and 7, in both embodiments a deflector
body 226 is situated behind the front opening 228 in the reverse
gate housing. The deflector body 226 is designed to split the
incoming water discharged from the steering nozzle and divert the
resulting streams to the port and starboard sides and toward the
respective flow-reversing passages 206 and 206'.
[0041] Referring to FIG. 6, the deflector body 226 in accordance
with the first preferred embodiment comprises three vertical walls
230, 232 and 234, connected along a vertical line to form a central
juncture 236. The central juncture is located midway between the
reversing passage inlets. The three vertical walls are preferably
attached or joined to the top and bottom walls of the reverse gate
housing. The flow-splitting wall 230 of the deflector body is
longitudinally straight and preferably planar. The flow-splitting
wall 230 lies in the reverse gate midplane and extends forward from
the central juncture 236 of the walls. The flow-deflecting walls
232 and 234 of the deflector body are laterally curved in the shape
of respective arcs. One arc 232 curves from the central juncture
236 toward the inlet of the reversing passage 206 on the port side
of the reverse gate; the other arc 234 curves from the central
juncture 236 toward the inlet of the reversing passage 206' on the
starboard side of the reverse gate. The concave side of each
flow-deflecting wall 232 and 234 faces toward the opening 228 in
the front of the reverse gate. The flow-deflecting walls 232 and
234 respectively guide or deflect incoming water toward the
respective inlets of the opposing reversing passages 206 and 206'.
The incoming stream of water is split by the flow-splitting wall
230 into two streams which respectively flow along the front
surfaces of the flow-deflecting walls 232 and 234. The port surface
of the flow-splitting wall 230 and the front surface of the
flow-deflecting wall 232 on the port side form a continuous surface
having a J-shaped contour which redirects one stream of incoming
water toward the port reversing passage 206; similarly, the
starboard surface of the flow-splitting wall 230 and the front
surface of the flow-deflecting wall 234 on the starboard side form
a continuous surface having a J-shaped contour which redirects the
other stream of incoming water toward the starboard reversing
passage 206'.
[0042] In accordance with the first preferred embodiment, each
flow-deflecting wall 232 or 234 terminates at a sufficient distance
from the opposing curved outer wall 216 and 216', and each curved
outer wall 214 and 214' is suitably oriented, so that some water
discharged from the steering nozzle, when the latter is steered to
one side, is directed by the curved outer wall on that side,
through the aperture and out the discharge opening on the opposite
side of the lateral steering passage. For instance, water which
flows around the flow-deflecting wall 232 is directed to the
starboard discharge opening 220' of the lateral steering passage;
while water which flows around the flow-deflecting wall 234 is
directed to the port discharge opening 220 of the lateral steering
passage.
[0043] Thus the reverse gate in accordance with the first preferred
embodiment shown in FIGS. 4-6 is able to produce reverse thrust and
lateral steering thrust, the latter being directed so that the boat
steers in reverse like an automobile.
[0044] The deflector body in accordance with the second preferred
embodiment, shown in FIGS. 7-9, has a shape similar to that of the
first embodiment described above, i.e., three vertical walls
connected at a vertical juncture to form back-to-back J shapes
having a common spine. The deflector body of the second preferred
embodiment differs from the deflector body of the first preferred
embodiment in two respects: (1) the deflector body of the second
embodiment is freely pivotable about a vertical axis between limit
stops (the limit position is shown in FIG. 9), whereas the
deflector body of the first embodiment was fixed; and (2) the angle
of curvature (and lateral span) of each flow-deflecting wall of the
second embodiment is greater than the angle of curvature (and
lateral span) of the flow-deflecting walls of the first embodiment.
These differences are related: pivoting of the deflector body in
either direction makes it possible to extend the length of the
flow-deflecting walls without decreasing the gap between the end of
one flow-deflecting wall and the opposing curved outer wall 214 or
214'. Any decrease in the gap length would decrease the volume of
water which can flow through the gap, other factors being equal.
Also, the greater angle of curvature of the flow-deflecting walls
allows more water to be diverted toward the flow-reversing
passages. This increases reversing thrust significantly without
diminishing the steering thrust.
[0045] In the case of a pivoting deflector body, the flow-splitting
vertical wall 238 acts as a leading rudder. The leading rudder 238
is pivotably coupled to a pair of pivot pins 240 and 242, as shown
in FIG. 7. Alternatively, the leading rudder can be mounted to a
pivot shaft which passes through the leading rudder, the axis of
the shaft lying in the plane of the rudder. Each of the
flow-deflecting walls 232' and 234' extends along a circular arc
having an angle greater than the arc angle in the first embodiment.
The deflector body is pivotable about a vertical pivot axis between
limit positions (one of which is shown in FIG. 9) dictated by limit
stops strategically placed on the port and starboard sides of the
reverse gate housing. For example, limit stops (not shown) may be
integrally formed on the top or bottom wall of each flow-reversing
passage.
[0046] The reverse gate in accordance with the second preferred
embodiment operates as follows. When the steering nozzle 72 is
centered as shown in FIG. 8, the steering nozzle discharge is split
by the leading rudder 238. The respective streams are then diverted
toward the respective flow-reversing passages 206 and 206' by the
respective flow-deflecting walls 232 and 234 of the deflector body.
Steering, i.e., turning the steering nozzle about its pivot axis,
in one direction applies unequal forces on the two sides of the
deflector body, causing it to pivot in the opposite direction. The
leading rudder 238 still splits the incoming stream in two. The
major portion of the nozzle discharge is directed to the side
toward which the steering nozzle is turned; the remainder of the
nozzle discharge is directed by the leading rudder to the opposite
side. Because the deflector body is now turned, the tips of the
flow-deflecting walls 232 and 234 are not symmetrically located.
There is a large gap between the tip of the flow-deflecting wall in
the path of the major stream, while the gap on the other side is
substantially closed. In the example shown in FIG. 9, one part of
the major stream is diverted toward the flow-reversing passage 206
on the port side; another part of the major stream will flow
through the gap between the flow-deflecting wall 232 and the
opposing outer curved wall 214 and then out the steering passage
discharge opening 220' on the starboard side. Conversely, the
majority of the nozzle discharge will flow out the discharge
opening of the starboard flow-reversing passage and the port
discharge opening of the steering passage when the steering nozzle
is turned to starboard. This design produces high reverse thrust
and high lateral steering thrust when the boat is shifted into
reverse.
[0047] The deflector body in accordance with the preferred
embodiments comprises a pair of vertical surfaces. One vertical
surface extends straight from a first point adjacent the front
opening to a second point located rearward of the first point and
then curves along an arc from the second point to a third point.
The other vertical surface extends straight from a fourth point
adjacent the front opening to a fifth point located rearward of the
fourth point and then curves along an arc from the fifth point to a
sixth point. The first and fourth points are separated by the
thickness of the leading edge of the deflector body. The arcs are
equal to each other and preferably greater than 90 degrees. The
third and sixth points are symmetrically located on opposing sides
of a plane of symmetry defined by a plane midway between the
straight portions of the vertical surfaces. The transitions from
the straight portions to the curved portions at the second and
fifth points are smooth. The deflector body preferably pivots
freely over a range of angles dictated by the location of the limit
stops. Alternatively, the pivotable deflector body may be coupled
to have an angular position which is a function of the angular
position of the steering nozzle.
[0048] While the invention has been described with reference to
preferred embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation to the teachings of the invention
without departing from the essential scope thereof. Therefore it is
intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments
falling within the scope of the appended claims.
[0049] As used in the claims, the term "longitudinal" refers to a
direction generally parallel to the centerline axis of a water jet
propulsion system; the term "lateral" refers to a direction
generally perpendicular to the longitudinal direction and generally
parallel to a reverse gate pivot axis; and the term "vertical"
refers to a direction generally perpendicular to the plane defined
by the longitudinal and lateral axes. Also, as used in the claims,
the term "duct" may comprise a single part or a plurality of
assembled parts. For example, in the disclosed preferred
embodiment, the inlet housing, stator housing and exit nozzle form
a "duct". However, the present invention encompasses forming the
inlet housing and stator housing as one piece, forming the stator
housing and the exit nozzle as one piece, forming the inlet housing
as two pieces, forming the stator housing as two pieces, and so
forth. All such variations fall within the meaning of "duct" as
that term is used in the claims.
* * * * *