[0001] The invention relates to a water jet propulsion apparatus for a vessel or a watercraft,
comprising a rearwardly projecting water jet nozzle, a motor-driven impeller pump,
whose impeller is arranged in a tubular housing and is fixed to the rear end of an
forwardly extending motor-driven shaft, a delivery duct connecting the rear end of
the impeller housing with the water jet nozzle, and a forwardly extending water-intake
channel connecting a water-inlet opening at the forward end of the impeller housing
with a water-intake opening which communicates with the water surrounding the vessel.
A water jet propulsion apparatus of this kind is known from the documents US-A-3.757.728,
US-A-3.934.538 and US-A-3.943.876.
[0002] In the known water jet propulsion apparatuses of this kind, the water-inlet opening
connected with the water-intake channel and provided in the rear end of the impeller
housing extends over the whole cross-section of the impeller housing, so that the
pump impeller will receive water in the whole circular area thereof, both under and
over the level of the axis of the impeller shaft. This brings about some troubles
in the water flow through the water-intake channel, with the effect of reducing the
propulsive efficiency of the water jet propulsion apparatus.
[0003] The object of the invention is to provide a water jet propulsion apparatus for a
vessel or watercraft, of the type as disclosed above, whereby owing to the features
of its quite simple and not much expensive construction, a better propulsive efficiency
is ensured, jointly with a reduced noise and a lesser air pollution.
[0004] According to the invention, in a water jet propulsion apparatus as stated in the
preamble of claim 1, the problem arising from a reduction in the propulsive efficiency
of the water jet propulsion apparatus, is solved by the feature that the water-inlet
opening provided at the forward end of the impeller housing and connected with the
water-intake channel, lies exclusively underneath the level of the axis of the impeller
shaft.
[0005] Therefore, in the water jet propulsion apparatus according to the invention, the
pump impeller receives water from the sea only in its lower half, so that it is fed
with sea water only in its half lying underneath the level of the axis of the impeller
shaft.
[0006] Owing to this feature of the water jet propulsion apparatus according to the invention,
the wet surface of the water inlet opening in the forward end of the impeller housing,
and then also any resulting friction, are sensibly reduced. This prevents any troubles
from being produced in the sucked water flow through the water-intake channel. These
troubles are further eliminated according to another improvement of the invention,
by the feature that when navigating under a normal load, the water line arrives substantially
at the level of the axis of the impeller shaft, and/or the impeller shaft is rotatably
supported in a bushing arranged as close as possible to the forward end of the impeller
housing, so that only a very short length of the shaft carrying the pump impeller,
projects into the impeller housing.
[0007] The forward end of the impeller housing can be closed, with the exception of the
water-inlet opening lying underneath the level of the axis of the impeller shaft.
[0008] According to a further improvement of the invention, an auxiliary inlet opening can
be provided at the forward end of the impeller housing over the level of the axis
of the impeller shaft, and this auxiliary opening communicates with a duct which is
connected or connectable with the ambient air and/or with the exhaust manifold of
the motor and/or with the discharging duct for the motor-cooling water.
[0009] The fact that the exhaust gases from the motor can be conveyed into the impeller
housing at the forward end thereof, renders it possible to have the exhaust gases
mixed with the sucked sea water flow. This causes the flux density of the pumped water
flow to be reduced, so that the vibrations affecting the pump impeller and the resulting
noises are reduced. Moreover, the exhaust gases from the motor are efficaciously scrubbed
and cooled, whereby a lesser air pollution is ensured.
[0010] The water-inlet opening provided at the forward end of the impeller housing, and
connected with the water-intake channel, may be shaped and arranged as desired. In
one particularly advantageous embodiment of the invention, the said water-inlet opening
is formed as a sector of a circle, the center of which lies on the axis of the impeller
shaft, semicircle underneath a substantially horizontal diameter intersecting the
axis of the impeller shaft.
[0011] Also the auxiliary inlet opening provided at the forward end of the impeller housing,
over the level of the axis of the impeller shaft, may be shaped and arranged as desired.
In one particularly advantageous embodiment of the invention, the said auxiliary inlet
opening is formed as a sector of a circle, the center of which lies on the axis of
the impeller shaft, or as a semicircle over a substantially horizontal diameter intersecting
the axis of the impeller shaft.
[0012] Other advantageous improvements according to the invention form the object of the
other dependent claims.
[0013] The particular features of the invention and the advantages arising therefrom, will
appear more in detail in the specification of two preferred embodiments, which are
shown by way of non-limiting examples in the accompanying drawings, in which:
Figure 1 is a sectional view showing one embodiment of the water jet propulsion apparatus
for a vessel or watercraft, according to the invention, in which the tubular housing
of the pump impeller is arranged inside the bottom of the vessel.
Figure 2 is a sectional view taken on line II-II in Figure 1.
Figure 3 is a sectional view showing a further embodiment of the water jet propulsion
apparatus according to the invention, in which the tubular housing of the pump impeller
consists of a tubular body which is external to, and is attached to the vessel's or
watercraft's bottom.
[0014] Diagrammatically shown in Figure 1 is the astern region of a vessel or watercraft,
within which a tubular housing 1 is fitted, and is arranged at such a level that approximately
the lower half thereof will be filled with water, as indicated by arrow L. A delivery
duct 22 terminating with a nozzle 2, extends from the aft end side of, and is substantilly
coaxial to the tubular housing 1. The said delivery duct 22 is arranged in the fore-and-aft
direction of the vessel or watercraft, and extends out of the transom board 3 thereof.
The water jet for propulsion of the vessel or watercraft is ejected from the rear
end nozzle 2 of the delivery duct 22. The tubular housing 1 has its fore end side
connected with a lower water-intake channel 4 which is directed toward the vessel's
or watercraft's head. The rear end of the lower water-intake channel 4 is connected
with a water-inlet opening 15 at the forward end of the tubular housing 1. The forward
end of the water-intake channel 4 is connected with a water-intake opening 14 which
is provided in the vessel's or watercraft's bottom for sucking the water surrounding
the vessel. The said lower water-intake channel 4 is inclined downward and is directed
toward the vessel's or watercraft's head. The tubular housing 1 is further provided
at its fore end side with an auxiliary upper inlet opening 14 connected with a duct
5 which in turn is connected or connectable with the ambient air, and/or with the
exhaust manifold, and/or with the duct for discharging the water cooling the vessel-
or watercraft-propelling engine or engines.
[0015] In the illustrated embodiment, the water-inlet opening 15 provided at the foward
end of the tubular housing 1 and connected through the water-intake channel 4 with
the water-intake opening 14, is formed as a semicircle underneath a substantially
horizontal diametrical wall which separates this lower water-inlet opening 15 from
the auxiliary upper inlet opening 16. Also the auxiliary inlet opening 16 provided
at the forward end of the tubular housing 1 and connected with the upper duct 5, is
formed as a semicircle over the substantially horizontal diametrical wall, between
the two openings 15 and 16.
[0016] A pump impeller 8 is arranged in the tubular housing 1 and is secured to an impeller
shaft 7 rotatably supported in a bushing 6 which is fixed on the partition wall between
the two openings 15 and 16. The impeller 8 is formed as a propeller and constitutes
the rotor of the suction pump of the water jet propulsion apparatus of the vessel
or watercraft. Owing to the propeller 8 being arranged as close as possible to the
forward end of the housing 1, the propeller-driving shaft 7 does not extend, or extends
only in a slight degree into the tubular housing 1, as it clearly appears in Figure
1. Through a thrust bearing 9 and further means known per se, the shaft 7 driving
the propeller 8 is connected as usual to the shaft of the not shown engine or engines.
A stator 10 with spaced diffuser vanes is advantageously provided in the delivery
duct 22 by which the tubular housing 1 is connected to the nozzle 2. When navigating
under a normal load, the water-line L arrives substantially at the level of the propeller
shaft 7.
[0017] Therefore, in the above-disclosed water jet propulsion apparatus the impeller 8 is
fed with sea water only in part, and only into its lower half, through the water-inlet
opening 15 that lies underneath the level of the axis of the propeller shaft 7, and
is connected with the water-intake opening 14 through the water-intake channel 14.
The upper half of the pump impeller 8 can be fed at will by means of the duct 5, or
can be even left unfed. More particularly, the upper duct 5 can be closed and opened
at will, and can be connected with the exhaust manifold of the motor, and at the same
time also with the motor-cooling water discharge duct, or it can be connected only
with the exhaust manifold of the motor, or only with the motor-cooling water discharge
duct. The said upper duct 5 can be simply connected to the ambient air, or it may
be even omitted and, in this instance, the forward end of the impeller housing 1 can
be entirely closed over the bushing 6 and over the level of the axis of the impeller
shaft.
[0018] According to a further embodiment of the invention, at the aft end side of the delivery
duct 22 with the nozzle 2, a means is provided for orienting the water jet for propulsion
of a vessel or watercraft, so that it performs the function of a rudder. This means
consists of a water jet-orienting sleeve 11 which by means of diametrically opposite
arms 111 is pivotably connected to the free aft end side of the delivery duct 22 ending
with the nozzle 2, so as to be angularly movable in a horizontal plane, in both directions
relative to the longitudinal axis of the nozzle 2. The water jet-orienting sleeve
11 is provided on the lower portion of its peripheral wall with a downwardly inclined,
reverse motion duct 12 which is turned toward the vessel's or watercraft's head. A
shutter member 13 is provided in the water jet-orienting sleeve 11 and is hingedly
connected to the downstream rim portion - relative to the direction in which a propulsive
water jet is ejected, of the opening between the solidarized reverse motion duct 12
and water jet-orienting sleeve 11. The hinged shutter member 13 is so mounted as to
be swingable from a position in which it closes the reverse motion duct 12, into a
position shown by dash-and-dot lines, in which it closes the water jet-orienting sleeve
11, and deflects the water jet flow through the reverse motion duct 12, whereby a
vessel or watercraft is imparted a backward thrust.
[0019] Thus, thanks to the device comprising the angularly movable water jet-orienting sleeve
11, with the reverse-motion duct 12 and the shutter member 13, the motion is not reversed
by reversing the direction of rotation of the pump impeller 7, or by reversing the
inclination of the blades of the pump impeller 7, when the said impeller is in form
of a propeller with orintable blades, but the motion is reversed simply by moving
the shutter member 13 from the position shown by solid lines in Figure 1, into the
position shown by dash-and-dot lines in the said Figure 1. Both during the forward
and the reverse motion, the pump impeller receives sea water always in the same direction,
and sends the sea water into the delivery duct 22 through its end nozzle 2. Both when
the vessel or watercraft is moved forward or backward, either at low or at a high
speed, the pump impeller 8 is fed with sea water always through the water-inlet opening
15 lying underneath the level of the axis of the impeller shaft.
[0020] In the embodiment of the water jet propulsion apparatus for a vessel or watercraft,
according to Figure 3, the propeller 8 that constitutes the pump impeller of the water
jet propulsion apparatus, is caused to protrude from the vessel's or watercraft's
transom board 3, close to the area at which the transom board is connected with the
vessel's or watercraft's bottom. In this instance, the propeller 8 may be a propeller
emerging partly from the water line L. More particularly, the axis of rotation of
propeller 8, and then the propeller-driving shaft 7, are inclined upwardly from the
horizontal plane. The tubular housing 20 in which the propeller 8 is arranged, consists
in this embodiment of a tubular body, which is attached to the transom board 3 lower
portion connected with the vessel's or watercraft's bottom. Like the impeller housing
1 according to the former embodiment, the tubular body 20 is provided on its aft end
side with a delivery duct 22 terminating with a nozzle 2 and which is substantially
equal to the delivery duct of the former embodiment. Also the said delivery duct 22
with the nozzle 2, carries a water jet-orienting sleeve 11 which is like the above
described one, wherefore the members of this latter sleeve are designated by the same
reference numerals.
[0021] The tubular body 20 of the impeller housing is provided on its fore end side with
a tubular lower extension arranged below the vessel's or watercraft's bottom, whereby
the forward open, water-intake channel 24 is formed together with the underside of
the vessel's or watercraft's bottom. The water-intake channel 24 is connected with
the lower portion lying under the water of the impeller housing 20, and the upper
duct 25 for venting the exhaust gases and/or for discharging the engine-cooling water
is provided inside the astern region of a vessel or watercraft and is connected with
the upper portion of the tubular impeller housing 20. Therefore, also in this embodiment,
the propeller 8 dips partly into the water (arrow L indicating the water line) at
least when navigating, and preferably substantially by its lower half. The exhaust
gases from the engine or engines and/or the engine-cooling water may be fed to the
propeller upper half and are thus mixed with the sucked water flow from which the
propulsive water jet is formed. This second embodiment turns particularly to advantage,
because it permits to easily convert any type of conventional propeller drive into
a water jet propulsion apparatus.
[0022] The water jet propulsion apparatus according to the invention, affords a higher efficiency
in that any troubles in the water flow through the water-intake channel are eliminated.
Thanks to the possibility of having the exhaust gases from the engine or engines mixed
with the sucked water flow from which the propulsive water jet is formed, the flux
density of the discharge water flow is reduced, so that any vibrations affecting the
pump impeller, and so any noise generation when navigating, are abated. On the other
hand, the exhaust gases from the engine or engines are also more efficaciously cooled
and scrubbed by the considerable outputs of sucked water, so that a lesser air pollution
will be produced.
1. A water jet propulsion apparatus for a vessel or a watercraft, comprising:
a) a rearwardly projecting water jet nozzle (2),
b) a motor-driven impeller pump, whose impeller (8) is arranged in a tubular housing
(1,20) and is fixed to the rear end of a forwardly extending motor-driven shaft (7),
c) a delivery duct (22) connecting the rear end of the impeller housing (1,20) with
the water jet nozzle (2),
d) a forwardly extending water-intake channel (4,24) connecting a water-inlet opening
(15) at the forward end of the impeller housing (1,20) with a water-intake opening
(14) which communicates with the water surrounding the vessel,
characterized in that
e) the water-inlet opening (15) provided at the forward end of the impeller housing
(1,20) and connected with the water-intake channel (4,24) lies exclusively underneath
the level of the axis of the impeller shaft (7).
2. The apparatus according to Claim 1, characterized in that the water-inlet opening
(15) provided at the forward end of the impeller housing (1,20) underneath the level
of the axis of the impeller shaft (7) and connected with the water-intake channel
(4,24), is formed as a sector of a circle, which center lies on the axis of the impeller
shaft (7).
3. The apparatus according to Claim 1, characterized in that the water-inlet opening
(15) provided at the forward end of the impeller housing (1,20) and connected with
the water-intake channel (4,24), is formed as a semicircle underneath a substantially
horizontal diameter intersecting the axis of the impeller shaft (7).
4. The apparatus according to any of the preceding Claims, characterized in that the
forward end of the impeller housing (1,20) is closed, with the exception of the water-inlet
opening (15) lying underneath the level of the axis of this impeller shaft (7).
5. The apparatus according to any of Claims 1 to 3, characterized in that an auxiliary
inlet opening (16) provided at the forward end of the impeller housing (1,20) over
the level of the axis of the impeller shaft (7), communicates with a duct (5,25) which
is connected or connectable with the ambient air, and/or with the exhaust manifold
of the motor, and/or with the motor-cooling water discharge duct.
6. The apparatus according to Claim 5, characterized in that the auxiliary inlet opening
(16) provided at the forward end of the impeller housing (1,20) over the level of
the axis of the impeller shaft (7) is formed as a sector of a circle, the center of
which lies on the axis of the impeller shaft (7), or as a semicircle over a substantially
horizontal diameter intersecting the axis of the impeller shaft (7).
7. The apparatus according to any of the preceding Claims, characterized in that when
navigating under a normal load, the water line L arrives substantially at the level
of the axis of the impeller shaft (7).
8. The apparatus according to any of the preceding Claims, characterized in that the
impeller shaft (7) is rotatably supported in a bushing (6) arranged as close as possible
to the forward end of the impeller housing (1,20), so that only a very short length
of the shaft (7) carrying the pump impeller (8) projects into the impeller housing
(1,20).
9. The apparatus according to any of the preceding Claims, characterized in that the
pump impeller (8) is a propeller.
10. The apparatus according to any of the preceding Claims, characterized in that the
impeller housing (1), the forward directed water-intake channel (4) and the auxiliary
duct (5) are arranged within the astern region of the vessel's or watercraft's bottom,
just before the transom board (3), and the delivery duct (22) with the water jet nozzle
(2) extends out of the transom board aft side.
11. The apparatus according to any of the preceding Claims 1 to 9, characterized in that
the impeller (8) is caused to protrude from the transom board (3), and the impeller
housing consists of a tubular body (20) which is attached externally to the vessel's
or watercraft's bottom, and is provided on its aft end side with the delivery duct
(22) and with the water jet nozzle (2), and on its fore end side with a forward directed,
tubular lower extension, that forms the water-intake channel (24) together with the
underside of the vessel's or watercraft's bottom, particularly in the area at which
the transom board (3) is connected with the vessel's or watercraft's bottom.
12. The apparatus according to any of the preceding Claims, characterized in that in the
delivery duct (22) of the impeller pump a stator (10) with spaced diffuser vanes is
provided.
13. The apparatus according to any of the preceding Claims, characterized in that a water
jet-orienting means (11,12,13) is provided at the aft end of the water jet nozzle
(2), which functions as a rudder and as a motion reverser.
14. The apparatus according to Claim 13, characterized in that the means for orienting
the propulsive water jet consists of a water-jet orienting sleeve (11), which is pivotably
connected to the free aft end side of the delivery duct (22) ending with the water
jet nozzle (2) so as to be angularly movable in a horizontal plane, in both directions
relative to the longitudinal axis of the said delivery duct (22) and its water jet
nozzle (2), the water jet-orienting sleeve (11) being provided with a lower reverse
motion duct (12) which is inclined downwardly and is turned forwardly and being also
provided with a hingedly connected shutter member (13), which is alternately swingable
into a position in which it closes the reverse motion duct (12), and into a position
in which it closes the water jet-orienting sleeve (11) and deflects the water jet
flow through the said reverse motion duct (12).