[0001] The invention relates to a water jet propulsion apparatus for a watercraft or a vessel,
particularly for a mine hunter.
[0002] A water jet propulsion apparatus by which the maximum propulsive efficiency is attainable,
is generally utilized for a conveniently high-speed navigation during a vessel's passage
from one place to another. The higher propulsive efficiency of such a water jet propulsion
apparatus does not afford a sufficiently noiseless navigation of the vessel, as needed
for a mine location operation. Thus, the water propulsion apparatus fo this type is
not usable when a very low-speed navigation as noiseless as possible is required,
as it is the case with a mine hunter. Another type of water jet propulsion apparatus
can be used with advantage also in this instance, which is so made that the least
possible noise will be generated, and a very low-speed navigation is permitted. However,
with this latter type of water jet propulsion apparatus, a high-speed navigation as
required for a vessel's passage from one place to another, occurs under less favourable
conditions. Therefore, the alternative arises particularly with mine hunters, of accepting
a relatively low propulsive efficiency during the navigation, or of providing further
propulsive means adapted for a high-speed navigation, to be used when a particularly
noiseless navigation is not required.
[0003] The invention is base on the problem of providing a water jet propulsion apparatus
which owing to the features of its relatively simple and not much expensive construction,
will permit to navigate according to circumstances, alternatively in both navigating
modes, i.e., in the noiseless low-speed mode, and in the high propulsive efficiency
high-speed mode.
[0004] The invention solves the said problem by the provision of a water jet propulsion
apparatus for a watercraft or a vessel, particularly for a mine hunter, comprising
at least one first water jet thruster unit constructed for high-speed navigation and
provided with its own direction and inversion control means, at least one second water
jet thruster unit constructed for low-speed noiseless navigation and provided with
its own direction and inversion control means, and one water pumping system associated
with both of the first and second water jet thruster units and alternatively connectable
to the one or the other of these first and second thruster units.
[0005] In a preferred embodiment of the water jet propulsion apparatus according to the
invention, the second water jet thruster unit for low-speed noiseless navigation generates
a propulsive water jet at a lower level, particularly under the level of the water
surface close to the underside of the vessel's hull, then the first water jet thruster
unit for high-speed navigation, which particularly generates a propulsive water jet
substantially at the level of the water surface.
[0006] Both the first water jet thruster unit for high-speed navigation and the second water
jet thruster unit for low-speed noiseless navigation and the associated water pumping
system can be constructed in any manner being suitable for the respective specific
purpose. However, in a preferred embodiment of the water jet propulsion apparatus
according to the invention, the water pumping system comprises a pump with a forwardly
extending water-intake channel and a rearwardly extending water discharge duct, and
the first water jet thruster unit for high-speed navigation consists of a nozzle provided
at the rear end of the water discharge duct, with its axis being oriented in the longitudinal
direction of the vessel, while the second water jet thruster unit for low-speed noiseless
navigation consists of a grate of parallel deflector vanes which extend transversally
to the longitudinal direction of the vessel and are rearwardly and downwardly inclined
relative to a horizontal plane, the said deflector vanes grate being located or locatable
within a substantially horizontal water outlet opening in the vessel's bottom and
water-deflecting means being provided in the discharge duct of the pump for connecting
this discharge duct alternatively with the nozzle at its end or with the water outlet
opening provided with the deflector vanes grate.
[0007] Also the direction and inversion control means associated with the first water jet
trhuster unit and with the second water jet thruster unit can be constructed in any
suitable manner. In a preferred embodiment of the water jet propulsion apparatus according
to the invention, the direction and inversion control means of the first water jet
thruster unit consisting of a nozzle, comprise a rearwardly extending water jet-orienting
sleeve which is connected to the free end of the nozzle so as to be swingable in both
directions in a horizontal plane, and a forwardly directed and downwardly inclined
backward motion duct which is branched off the water jet-orienting sleeve and has
its outlet opening turned toward the vessel's head, a hingedly connected shutter member
being fitted in the said water jet orienting sleeve, for alternatively closing the
backward motion duct and the rear end of the water jet-orienting sleeve. The direction
and inversion control means of the second water jet thruster unit, formed by the deflector
vanes gate, preferably consist of means for turning the circularly shaped deflector
vanes gate around a vertical central axis.
[0008] The water jet propulsion apparatus according to the invention, can be quite easily
and efficaciously adapted either to a high-speed navigation during which the maximum
advantage is taken of the water jet propulsive efficiency, or to a noiseless low-speed
navigation that permits a particular handling of a vessel at very low speeds. All
this is achieved with a construction which is not much expensive and is relatively
simple from the mechanical viewpoint, and which permits such an adaptation of the
water jet propulsion apparatus to be easily and quickly carried out while navigating.
[0009] Other features further improving the water jet propulsion apparatus according to
the invention, are the subject of the other dependent claims.
[0010] The particular features of the invention, and the advantages arising therefrom, will
appear more in detail in the specification of some preferred embodiments thereof,
which are shown by way of non-limiting examples in the accompanying drawings, in which:
Figure 1 shows a diagrammatic, vertical longitudinal section through one embodiment
of the water jet propulsion apparatus according to the invention, in which the water
jet thruster unit for high-speed navigation is activated, and the water jet thruster
unit for low-speed noiseless navigation is desactivated.
Figure 2 shows a section like that shown in Figure 1, in which the water jet thruster
unit for high-speed navigation is desactivated and the water jet thruster unit for
low-speed noiseless navigation is activated.
Figure 3 is a top plan view of the direction and inversion control means of the water
jet thruster unit for high-speed navigation, as in the embodiment of the water jet
propulsion apparatus according to Figures 1 and 2.
Figure 4 is a side elevational view with parts in a longitudinal vertical section,
showing another embodiment of the water jet propulsion apparatus according to the
invention.
Figure 5 is a top plan view, with parts in section, of the embodiment of the water
jet propulsion apparatus according to Figure 4.
Figure 6 is a vertical sectional view in an enlarged scale, taken on line VI-VI in
Figure 5.
Figure 7 shows a modification of the embodiment according to Figures 4 to 6, in a
similar top plan view as in Figure 5.
[0011] Figures 1 to 3 illustrate a first embodiment of the water jet propulsion apparatus
according to the invention, for a watercraft or a vessel, particularly for a mine
hunter. This water jet propulsion apparatus, arranged in the astern region of the
vessel, comprises a first water jet thruster unit A for high-speed navigation and
a second water jet thruster unit B for low-speed noiseless navigation. Both the first
and the second water jet thruster units A, B are associated with the same diagrammatically
shown pump 1 which is driven by a not shown motor. The pump 1 is fitted with a water
intake channel designated by reference numeral 2, which opens into the water and has
a water-intake inlet (not shown) which is provided in the lower region of the vessel's
hull. The discharge duct 3 of pump 1 ends into a nozzle 5, which is substantially
close to the aft side of the vessel's transom board 4. The nozzle 5 is for a water
flow thereout causing a water jet to form with the highest propulsive efficiency,
and constitutes the first water jet thruster unit A for high-speed navigation. The
nozzle 5 is so arranged that its axis extends in the direction of the longitudinal
axis of the vessel's hull, and is located at such a level that the propulsive water
jet will be preferably discharged, substantially as a whole or at least in part, at
the level L of the water surface.
[0012] Downstream of nozzle 5 - relative to the water jet-discharge direction, a water jet
deflecting device is provided, which can be caused to perform the function of orienting
the thrust direction of the propulsive water jet, and thus a rudder function. The
said water jet deflecting device constitutes the direction control means of the first
water jet thruster unit H for high-speed navigation and consists of a water jet-orienting
sleeve 6 which by means of two diametrically opposite arms 106 is connected to the
nozzle 5 so as to be swingable around a vertical axis. The extreme positions into
which the water jet-orienting sleeve 6 is angularly movable, are shown by dash-and-dot
lines in Figure 3. More particularly, the water jet-orienting sleeve 6 can be angularly
moved in both senses of its swinging direction by about 30° to 35° relative to the
longitudinal axis of nozzle 5.
[0013] According to a further feature, the said device for deflecting the propulsive water
jet from nozzle 5, can be also caused to perform the function of a motion reverser
and comprises a backward motion duct 7, which is branched off the water jet-orienting
sleeve 6 in its lower part and is forwardly directed and downwardly inclined relative
to a horizontal plane. The outlet opening of this backward motion duct 7 is turned
substantially toward the vessel's head, so that a thrust component of the propulsive
water jet will be generated in the backward direction. The backward motion duct 7
is associated with a hinged shutter member 8 that is hingedly connected at 108 to
the aft portion of the edge by which the backward motion duct 7 is connected with
the water jet-orienting sleeve 6. The hinged shutter member 8 is alternatively swingable
into a position in which it closes the backward motion duct 7, so that the propulsive
water jet is allowed to flow through the water jet-orienting sleeve 6, and the vessel
is thus driven forward, and into a position in which it closes the water jet-orienting
sleeve 6 (as shown by dash-and-dot lines in Figures 1 and 2), and is inclinedly arranged
relative to the vertical direction, so that the discharge water jet flow is deflected
through the backward motion duct 7, and a backward thrust component of the propulsive
water jet is thus generated, whereby the vessel is driven backward.
[0014] A tubular vertical guide 9 is arranged in an intersecting relation with the discharge
duct 3 of pump 1, and by its respective sections 109 and 209 extends both downwardly
and upwardly from the discharge duct 3. The upward section 209 is closed by a cover
12, while the downward section 109 is not shut and terminates with an opening 409
in the vessel's bottom. Slidably fitted in the tubular guide 9 is a coaxial tubular
slide 10 which carries an elbow-like tubular member 11. The inlet opening 111 of the
elbow-like tubular member 11 is formed in a skirt portion of the tubular slide 10
and is turned forwardly. The outlet opening 211 of the elbow-like tubular member 11
is arranged coaxial to the tubular guide 9, and is turned toward the open lower end
thereof. In this lower outlet opening 211 a circular grate 13 is arranged and is so
mounted as to be angularly movable over 360° around the median axis of the outlet
opening 211. The circular grate 13 is connected to a driving shaft 14 arranged coaxial
to the median longitudinal axis of the tubular guide 9. The driving shaft 14 is led
to the exterior of the tubular guide 9, by being passed through a supporting member
15 made integral with the elbow-like tubular member 11.
[0015] The grate 13 constitutes the second water jet thruster unit B for a low-speed noiseless
navigation and consists of a plurality of parallel deflector vanes which extend transversally
to the longitudinal direction of the vessel and are inclined downwardly and rearwardly,
preferably of about 30°, relative to the vessel's head. The discharge water flow through
the elbow-like tubular member 11 is vertically deflected downward, and by the said
deflector vanes is further deflected from its vertical flow direction, so that a horizontally
directed thrust component of the propulsive water jet will be generated. Moreover,
with the grate 13 of deflector vanes being angularly movable around the axis of the
outlet opening 211, the propulsive water jet can be oriented in any suitable direction
relative to the longitudinal axis of the vessel's hull, so that the grate 13 can be
caused to perform either the function of a rudder or of a motion reverser. The shaft
driving the grate 13 may be actuated in any suitable manner and, for example, it may
be either hydraulically, or electrically, or pneumatically, or manually operated,
and the actuating members can be directly controlled by the vessel's steering compartment.
[0016] As it clearly appears in Figures 1 and 2, the elbow-like tubular member 11 can be
vertically shifted into an uplifted inactive position (Figure 1), and into a lowered
down active position (Figure 2), the tubular guide 9 being of an adequate length.
Any suitable means, such as of the hydraulic, pneumatic, electric, and even manual
type, may be provided as actuator means for lifting up and lowering down the elbow-like
tubular member 11. When the elbow-like tubular member 11 is set in its uplifted inactive
position, its outlet opening 211 lies over the discharge duct 3, so that the way is
clear for the discharge water flow from pump 1 to nozzle 5. When the said elbow-like
tubular member 11 is moved into its lowered down inactive position (Figure 2), its
inlet opening 111 is caused to coincide with the discharge duct 3 of pump 1, and its
outlet opening 211 is arranged near the lower opening 409 of the tubular guide 9,
lying close to the underside of the vessel's hull. Thus, the way for the discharge
water flow from pump 1 to nozzle 5 is interrupted, while the outlet opening 211 of
the elbow-like tubular member 11 comes to be located at a lower level than the nozzle
5, and lies entirely under the water level. The outlet opening 211 of the elbow-like
tubular member 11 and the associated grate 13 of deflector vanes can be caused to
protrude from the bottom opening 409 of the tubular guide 9, or to extend in a flush
relation therewith.
[0017] The just disclosed constructional features of the second water jet thruster B are
particularly adapted for a water jet propulsion to be applied to a very low-speed
navigation, with an extremely reduced noise generation. This second water jet thruster
unit B has a propulsive efficiency which is lower than the propulsive efficiency as
afforded by the previously disclosed first water jet thruster unit A. However, owing
to the water jet being discharged under the water level, and being orientable in any
directions over 360°, it is possible to attain an extremely reduced noise generation,
and to achieve the best manoeuvrability of a vessel at the low speeds as required
for a mine location operation.
[0018] According to a further feature of the invention, the lower end 409 of the tubular
guide 9 may be suitably closed with a movable closing body extending thereover (not
shown), when the elbow-like tubular member 11 is set in its uplifted inactive position.
The tubular guide 9 may be also provided with a lateral inspection port 309 which
substantially lies at the level of, or slightly over the outlet opening 211 of the
elbow-like tubular member 11 - when this member is set in its uplifted inactive position,
and is closed by a hinged lid 16. Thanks to the said inspection port 309, it is possible
to service, for example cleaning, the grate 13 of deflector vanes at any moment, even
during the navigation, and without the vessel having to be hauled up.
[0019] The embodiment of the water jet propulsion apparatus according to Figures 4 to 6,
comprises one water jet thruster unit A constructed for a high-speed navigation, and
two water jet thruster units B constructed for a low-speed noiseless navigation, which
are disposed in symmetrical relationship relative to the median longitudinal axis
of the vessel. Each water jet thruster unit A,B is provided with its own direction
and inversion control means.
[0020] The water jet thruster units A,B are associated with one water pumping system comprising
a pump 1 with a forwardly extending water-intake channel 2 and a rearwardly extending
water discharge duct 3.
[0021] Just as in the embodiment according to Figures 1 to 3, the water jet thruster unit
A for high-speed navigation consists of a nozzle 5 provided at the rear end of the
water discharge duct 3. The axis of the nozzle 5 is oriented in the longitudinal direction
of the vessel. The direction and inversione control means associated with the nozzle
5, comprise - as disclosed for the embodiment according to Figures 1 to 3 - a rearwardly
extending water jet-orienting sleeve 6 which is connected to the free end of the nozzle
5 by a spherical joint, so as to be swingable in both directions in a horizontal plane.
Branched off the underside of the water jet-orienting sleeve 6 is a forwardly directed
and downwardly inclined backward motion duct 7, with its outlet opening being turned
toward the vessel's head. A shutter member designated by 8 in Figures 1 and 2, is
provided for closing the backward motion duct 7, and for leaving the water jet-orienting
sleeve 6 in open condition, and vice-versa. The nozzle 5 and the water jet-orienting
sleeve 6 with the backward motion duct 7, are located into a recess 21 in the stern
of the vessel. The pump 1 is driven by the shaft 20 of a motor.
[0022] Each water jet thruster unit B for low-speed noiseless navigation consists of a circular
grate 13 of parallel deflector vanes which extend transversally to the longitudinal
direction of the vessel and are rearwardly and downwardly inclined to a horizontal
plane. This deflector vanes grate 13 is housed into a substantially horizontal opening
409 formed in the bottom of the vessel, and is supported so as to be rotatable around
a substantially vertical axis, by a support 22. Two diametrically opposite secondary
water discharge ducts 23 are branched off the discharge duct 3 of the pump 1, and
are connected to the openings 409 formed in the bottom of the vessel, through the
respective deflector vane grates 13 of the two water jet thruster units B for low-speed
noiseless navigation. At the branching point of the said ducts 23, two flap valves
24 are provided, which close the inlets of the secondary water discharge ducts 23
and open the main water discharge duct 3, and vice-versa. The direction and inversion
control means associated with each one of the two water jet thruster units B for low-speed
noiseless navigation, consist of a manually or motor-operated pinion 24 in mesh with
a peripheral ring gear 25 of the deflector vanes grate 13, for angularly orientating
this grate.
[0023] The modified embodiment of the water jet propulsion apparatus according to Figure
7 differs from the embodiment according to Figures 4 to 6, only in that only one water
jet thruster unit B for low-speed noiseless navigation, is provided in this modified
embodiment. This thruster unit B is arranged in an eccentric position on one side
of the longitudinal median axis of the vessel, and is connected to the main water
discharge duct 3 of the pump 1 through a secondary discharge duct 23 and through a
flap valve system 24.
1. A water jet propulsion apparatus for a watercraft or a vessel, particularly for a
mine hunter, characterized by
a) at least one first water jet thruster unit (A) constructed for high-speed navigation
and provided with its own direction and inversion control means (6,7,8),
b) at least one second water jet thruster unit (B) constructed for low-speed noiseless
navigation and provided with its own direction and inversion control means (14;24),
c) one water pumping system (1) associated with both of the first and the second water
jet thruster units (A,B), and alternatively connectable to the one or the other of
these first and second thruster units.
2. The water jet propulsion apparatus according to claim 1, characterized in that the
second water jet thruster unit (B) for low-speed noiseless navigation generates a
propulsive water jet at a lower level than the first water jet thruster unit (A) for
high-speed navigation.
3. The water jet propulsion apparatus according to claims 1 and 2, characterized in that
the first water jet thruster unit (A) for high-speed navigation generates a propulsive
water jet substantially at the level of the water surface (L), while the second water
jet thruster unit (B) for low-speed noiseless navigation generates a propulsive water
jet under the level of the water surface (L), close to the underside of the vessel's
hull.
4. The water jet propulsion apparatus according to any one of the preceding claims, characterized
in that the water pumping system comprises a pump (1) with a forwardly extending water
intake channel (2) and a rearwardly extending water discharge duct (3), and the first
water jet thruster unit (A) for high-speed navigation consists of a nozzle (5) provided
at the rear end of the water discharge duct (3), with its axis being oriented in the
longitudinal direction of the vessel, while the second water jet thruster unit (B)
for low-speed noiseless navigation consists of a grate (13) of parallel deflector
vanes which extend transversally to the longitudinal direction of the vessel and are
rearwardly and downwardly inclined relative to a horizontal plane, said grate (13)
of deflector vanes being located or locatable within a substantially horizontal water
outlet opening (409) in the vessel's bottom and water-deflecting means (11,111,211;24)
being provided in the discharge duct (3) of the pump (1) for connecting this discharge
duct (3) alternatively with the nozzle (5) at its end or with the water outlet opening
(409) provided with the deflector vanes grate (13).
5. The water jet propulsion apparatus according to any one of the preceding claims, characterized
in that the water-deflecting means in the discharge duct (3) of the pump consist of
an elbow-like tubular member (11) with its inlet opening (111) being turned forward
and with its outlet opening (211) being provided with the deflector vanes grate (13)
and being turned downward, the said elbow-like member (11) being slidably fitted in
a substantially vertical tubular guide (9) which is arranged in intersecting relation
with the substantially horizontal discharge duct (3) of the pump (1) and opens into
the underside of the vessel's hull, means being provided for shifting the elbow-like
tubular member (11) in the tubular guide (9) from an uplifted inactive position in
which it leaves the discharge duct (3) open and allows the water to flow to the nozzle
(5) at the end of this duct, into a lowered down active position, in which its inlet
opening (111) is caused to coincide with the discharge duct (3) and its outlet opening
(211) provided with the deflector vanes grate (13), lies at the tubular guide lower
opening (409) in the underside of the vessel's hull, so that the communication between
the discharge duct (3) and its nozzle (5) is interrupted.
6. The water jet propulsion apparatus according to claim 5, characterized in that the
elbow-like tubular member (11) is mounted on a tubular slide (10) slidably supported
in the tubular guide (9).
7. The water jet propulsion apparatus according to claims 5 and 6, characterized in that
the tubular guide (9) is provided in its section (209) extending upwardly from the
discharge duct (3), with an inspection port (309) which is closable with a lid (16),
the said inspection port (309) being located substantially above the level of the
water surface (L), at the level of, preferably immediately over the outlet opening
(211) of the elbow-like tubular member (11), when this member is set in its uplifted
inactive position.
8. The water jet propulsion apparatus according to claims 5-7, characterized in that
with the elbow-like tubular member (11) being set in its lowered down active position,
the outlet opening (211) thereof, provided with the deflector vanes grate (13), is
disposed in a substantially flush relation with the open lower end (409) of the tubular
guide (9), or is caused to protrude slightly therefrom.
9. The water jet propulsion apparatus according to claim 4, characterized in that the
water deflecting means in the discharge duct (3) of the pump consist of a flap valve
system (24) provided at a point, in which at least one secondary water discharge duct
(23) is branched off the pump discharge duct (3) and is connected with the deflector
vanes grate (13), the flap valve system (24) being so constructed and actuated that
it will be alternatively caused to assume a position in which it closes the communication
between the pump discharge duct (3) and its nozzle (5), and opens the communication
between the pump discharge duct (3) and the secondary water discharge duct (23) leading
water to the deflector vanes grate (13), and a position, in which it opens the communication
with the nozzle (5) and closes the communication with the secondary water discharge
duct (23).
10. The water jet propulsion apparatus according to claim 9, characterized in that only
one secondary water discharge duct (23) is branched off the pump discharge duct (3)
and is connected with one deflector vanes grate (13) disposed within an opening (409)
in the underside of the vessel's hull.
11. The water jet propulsion apparatus according to claim 9, characterized in that two
diametrically opposite secondary water discharge ducts (23) are branched off the pump
discharge duct (3) and are connected with two deflector vane grates (13) disposed
in symmetrical relationship each within an opening (409) in the underside of the vessel's
hull.
12. The water jet propulsion apparatus according to claim 4, characterized in that the
direction and inversion control means of the first water jet thruster unit (A) formed
by a nozzle (5) comprise a rearwardly extending water jet-orienting sleeve (6) which
is connected to the free end of the nozzle (5) so as to be swingable in both senses
in a horizontal plane and a forwardly directed and downwardly inclined backward motion
duct (7) which is branched off the water jet-orienting sleeve (6) and has its outlet
opening turned toward the vessel's head, a hingedly connected shutter member (8) being
fitted in the said water jet-orienting sleeve (6), for closing alternatively the backward
motion duct (7) and the rear end of the water jet-orienting sleeve (6).
13. The water jet propulsion apparatus according to claim 4, characterized in that the
direction and inversion control means of the second water jet thruster unit (B) formed
by the deflector vanes grate (13), consist of means (24,25) for turning the circularly
shaped deflector vanes grate (13) around a vertical central axis.