Water jet propulsion apparatus

Abstract: The invention relates to a water jet propulsion apparatus for a watercraft or a vessel, particularly for a mine hunter. According to the invention 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), is combined with 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). One water pumping system (1) is associated with both of the first and the second water jet thruster units (A,B) and is alternatively connectable to the one or the other of these first and second thruster units (A,B).

Description: The invention relates to a water jet propulsion apparatus for a watercraft or a vessel, particularly for a mine hunter. A water jet propulsion apparatus by which the maximum propulsive efficiency is attainable, is generally utilized for 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. 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. 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. 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. 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. 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. The water jet propulsion apparatus according to the invention, can be quite easily and efficiently 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. Other features further improving the water jet propulsion apparatus according to the invention, are the subject of the other dependent claims. 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. 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. 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 A 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. 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. 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. 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. 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. 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. 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. 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. 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. 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 inversion 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. 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. 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.

Claims: 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. 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. 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. 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). 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. 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). 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. 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. 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). 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. 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. 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). 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.

Inventors: FANTACCI GIANFRANCO, INNOCENTI ENRICO, FANTACCI, GIANFRANCO, INNOCENTI, ENRICO
Applicants: INTERMARINE SPA, INTERMARINE S.P.A.
Application year: 1991
Main classification: B63H11
IPC codes: B63H11