EP0037865B1

EP0037865B1 - Valve system for controlling the direction of fluid discharge from a nozzle in a thruster system

Info

Publication number: EP0037865B1
Application number: EP19800301123
Authority: EP
Inventors: George Karstel; Thomas Alexander Mcconnell
Original assignee: Weir Pumps Ltd; Weir Warmtekracht BV
Current assignee: Weir Pumps Ltd; Weir Warmtekracht BV
Priority date: 1980-04-09
Filing date: 1980-04-09
Publication date: 1984-08-22
Also published as: EP0037865A1; DE3068995D1

Description

The present invention relates to a thruster system for use in marine craft including ducting for location in the hull of the craft, the ducting having a pair of opposed discharge outlets discharging externally of the hull, means for directing a fluid flow through the ducting to the discharge outlets and control means for controlling the flow discharge. More especially the system can be used in a ship's bowthrusting system.
Water jet propulsion systems are known in the marine art for propelling ships as an alternative to conventional propellor propulsion: this is particularly beneficial for use in water conditions where there would be a high risk of fouling of the propellor or where there is small water depth mitigating against the use of a propellor. Such a marine craft water jet propulsion system is shown in U.S. Patent 3,824,946, wherein an impeller driven by the main engine of the marine craft draws in water via an aperture in the craft's bottom and directs the water via ducting to a rearward discharge. The system additionally includes a pair of vanes located externally at the discharge and pivotal about parallel vertical axes whereby the discharge direction of the water jet can be varied to provide a steering effect. The conventional rudder can be dispensed with and the variable direction water jet has the advantage of enabling the craft to be manoeuvred even when the craft has little motion or way on. Further, the vanes of U.S. Patent US-A-3,824,946 can be set to divert the water jet through 180° and thereby provide rearward propulsion for the marine craft.
In the marine industry it is also established practice to fit ships with bow thrusting devices to improve manoeuvrability, thereby reducing dependence on tugs when moving in confined waters such as in rivers, canals or when docking or undocking. These use water jets created by impellers in the manner as shown in U.S. Patent US-A-3,824,946 but directed to have a transverse component of discharge.
Bow thrusting systems typically consist of a pump, which may be driven by an auxilliary diesel engine, electric or hydraulic motor, discharging through a system of ducting and/or flow control devices. One example of a previous bow thrusting system is described in published UK patent application No. 2007174A. The bow thrusting system of UK patent application No. GB-A-2007174 comprises lateral ducting providing opposed lateral water discharges in the forward section of the ship's hull; water is pumped to the ducting from an aperture in the ship's bottom. Vane means located centrally in the ducting are operable to direct the water to a selected one of the discharges or to both discharges. Additionally, nozzle means are provided in each discharge and controllable, for example by further vanes, whereby the water discharged from the ducting can be given a definite forward or rearward component of motion, in addition to a purely transverse discharge direction.
It is the main object of the present invention to provide a bow thrusting system which is of simplified construction but which enables a higher degree of ship manoeuvrability in comparison with prior systems. This object is met in the present invention by having each discharge outlet of the lateral ducting comprising a diverging outlet portion when viewed in plan view and by providing valve means to control the direction of fluid flow through each discharge outlet or preclude fluid flow from the outlet, comprising a pair of pivotal vanes at each discharge outlet having parallel pivot axes.
Preferably the parallel pivot axes of the vanes are located at the inlet to the diverging outlet portion so that a portion of each vane projects into the diverging outlet portion.
Preferably further, each diverging outlet portion has a divergence angle of approximately 90°. In operation of the above thruster system according to the present invention, the vanes at each discharge outlet can pivot in unison to control the direction of water discharge, or be pivoted in a contra-direction to close the discharge outlet when the water discharge is to recur from the other side only so as to create a turning movement on the vessel. Thus, with opposed transverse discharges in a ship's bow thrusting system, by selective operation of the valve vanes it is possible to achieve desired sideways movements and also forward and reverse motions: turning movements are also possible. There is no need for any additional central control vane system for selective water flows to the discharge outlets, since in the present invention this control is achieved by the vane pairs at the discharge outlets: this provides a simplification in the construction. Further in contrast to the system of UK patent GB-A-2007174 each vane pair of the present invention enables selection of a precise direction of water discharge from an outlet anywhere in the range from the pure transverse direction to a preferred angle of 45° on either side of said transverse direction: this enables a high degree of manoeuvrability to be achieved.
An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings wherein:-

Fig. 1 shows a bottom view of a bow thruster system in a ship, in accordance with the present invention.
Fig. 2 shows a cross-sectional side elevation of the thruster system of Fig. 1, and
Figs. 3 to 8 show various operational modes of the valve means of the thruster system of Figs. 1 and 2.

Referring to Figs. 1 and 2, a transverse thruster 1 is fitted into a ship's hull 2 towards the bow thereof and comprises a transverse duct 3 close to the bottom 4 of the hull 2 and a pair of venturi-type discharges (or nozzles) 5 at opposite ends of the duct 3 discharging externally of the hull 2. A central lateral duct 6 opens into the transverse duct 3 and houses a pump 7 comprising an axial flow impeller 8, flow to the impeller 8 being via a frustrum inlet 9 at the ships bottom 4. The impeller is mounted on a shaft rotor 10 and located by a thrust collar 11 and a sleeve bearing 12, and the rotor 10 is driven by a suitable motor (not shown) e.g. electric or hydraulic motor or a diesel engine, via a right angle gearbox 13 the outlet 14 from which is connected to the rotor 10 by coupling 15. The weight of the pump rotating element and the pump axial hydraulic thrust is carried on a thrust bearing located in the right angled gearbox. A shaft seal (25) is fitted to the rotor 10 below the coupling 15.
The pump 7 is set at as low as possible relative to the bottom of the ship to ensure that the impeller 8 is fully submerged under all conditions of ship loading. The discharges 5 on the other hand may or may not be submerged under all loading conditions.
Control of flow from each of the discharges 5 is achieved by diverter valves 16 each comprising a pair of parallel aerofoil vanes 17 fixed to parallel rotary shafts 18 supported in bearings 19. The shafts 18 are rotated by motors 20 (e.g. electrical or hydraulic) via gearboxes 21, and it is a feature of the arrangement that the shafts 18 (and vanes 17) of each valve 16 can be rotated in unison or in a contra-direction. As can be seen in Fig. 1 each discharge 5 includes a diverging outlet frustrum 22, and the axes of the shafts 18 of each valve 16 are located in the plane containing the frustum inlet end with a portion of each vane projecting into the frustrum.
In operation of the thruster 1, e.g. when the ship is manoeuvering in confined waters or is docking or undocking, the pump 7 is driven to discharge water into the duct 3 and the desired manoeuvre is achieved by controlled thrusting discharge of the water by means of diverter valves 16, as is illustrated in Figs. 3 to 6 and outlined as follows:

Fig. 3. For sideways motion to port (leftwards) the port valve 16 is closed by contra- rotation of vanes 17 to bring the vane leading tips into engagement with duct 3 and all the thrusting discharge is in a normal direction via the starboard discharge 5.
Fig. 4. This is similar to Fig. 3 but with the set up for sideways motion to starboard (rightwards).
Fig. 5. In this arrangement the vanes 17 of each valve 16 are pivoted in unison but with the vanes of one valve opposite to those of the other to give reverse motion.
Fig. 6. In this case the vanes 17 are oppositely pivoted relative to Fig. 5 for forward motion.

It is also possible to impart turning movement by pivoting the vanes 17 in unison as shown in Figs. 7 and 8: this operational mode is more effective where the thruster is located closer to the centre of turning (centre of gravity) of the ship.
Where the thruster is at a substantial distance from the centre of turning, it will be appreciated that the arrangements of Figs. 1 and 2 will also impart turning movements.
Valve position selection can be carried out remotely e.g. from the ship's bridge control room. The angle of pivoting of each vane may be varied for fine manoeuvres, and the thrust can be adjusted by varying the pump speed to give alteration of the water flow through the ducting.
The above valve arrangement provides efficient control of the direction of the discharging flow and hence correspondingly efficient thrusting in any of the desired directions as described.

Claims

1. A thruster system for use in marine craft including ducting for location in the hull of the craft, the ducting having a pair of opposed discharge outlets discharging externally of the hull, means for directing a fluid flow through the ducting to the discharge outlets and control means for controlling the flow discharge characterised in that each of the discharge outlets (22) comprises a diverging outlet portion when viewed in plan view (Fig. 1) and in that valve means (16) are provided to control the direction of fluid flow through each discharge outlet (22) or preclude fluid flow from the outlet, said valve means (16) comprising a pair of pivotal vanes (17) at each discharge outlet (22) having parallel pivot axes (18).

2. A thruster system as claimed in claim 1 characterised in that the parallel pivot axes (18) of the vanes (17) are located at the inlet to the diverging outlet portion (22) so that a portion of each vane (17) projects into the diverging outlet portion.

3. A thruster system as claimed in claim 1 or 2 characterised in that the vanes (17) are pivotal to bring a tip thereof into contact with a wall of the ducting (3) upstream of said diverging outlet portion (22).

4. A thruster system as claimed in any of the preceding claims characterised in that each diverging outlet -portion comprises wall portions (22) diverging outwardly in planar view to meet a side (2) of the marine craft.

5. A thruster system as claimed in claim 4 characterised in that the angle of divergence of the wall portions (22) approximates to 90°.

6. A thruster system as claimed in any one of the preceding claims characterised in that the valve means (16) are located in the throat of a venturi-nozzle discharge (5).

7. A thruster system as claimed in any one of the preceding claims characterised in that the vanes (17) are mounted on rotatable shafts (18) which are driven by motor means (20,21).

8. A thruster system as claimed in any one of the preceding claims, characterised in that the vanes (17) are of aerofoil form.