GB2260740A - Fluid pumps in propeller driven craft - Google Patents

Abstract

A device for pumping fluid in propeller driven craft comprises a substantially cylindrical open-ended shroud surrounding and coaxially aligned with the propeller 6, the internal diameter of the shroud varying along the length thereof. At least one fluid pipe 8 is provided, the outlet 10 of which is located on the internal surface of the shroud at the region 12 thereof with minimum internal diameter. The negative pressure induced at the minimum diameter region of the shroud on rotation of the propeller produces a pressure drop at the outlet of the or each fluid pipe. The device may be used for a number of different purposes, including the pumping of water from water-lubricated bearings, ventilation of the craft and as part of a ballast system for the craft. <IMAGE>

Description

IMPROVEMENTS IN AND RELATING TO FLUID PUMPS This invention relates to fluid pumps for pumping fluids in propeller driven craft. Fluid pumps are commonly used in floating vessels, for example, to drain bilge fluid or to circulate coolant through an engine or through a water-lubricated bearing. Known marine fluid pumps are rotary or piston type pumps, and are either driven by the main engine of the vessel, or require a separate motor or engine. Such pumps are expensive and require maintenance.

Where floating vessels have propellers to provide propulsion, it is common to provide a shroud surrounding the propeller. The shroud is generally cylindrical with open ends and is usually coaxially located with the axis of rotation of the propeller so as to enclose at least part of the area swept by the propeller blades. The propeller and the shroud may be above water to provide air propulsion, but more usually they are located underwater.

A device for pumping fluids in propeller drive craft, in accordance with the invention, comprises a substantially cylindrical open-ended shroud having an internal surface which has either convergent and divergent sections, or convergent, parallel and divergent sections surrounding and coaxially aligned with the propeller, and at least one fluid pipe having its outlet located on the inside circumference of the shroud at the minimum internal diameter thereof, so that the negative pressure induced at the minimum diameter of the shroud on rotation of the propeller produces a pressure drop at the outlet of the or each fluid pipe.

Such an arrangement may be used to pump fluid out of the outlet of the fluid pipe without requiring a separate engine or motor.

The fluid flow may be used, for example, to provide engine cooling where the engine is able to operate with raw water cooling (i.e. water drawn in from the water surrounding the vessel), to maintain continuous water circulation through a water-lubricated bearing, or to drain the bilges of the vessel. Such an arrangement consists merely of suitable fluid pipes and is therefore inexpensive and requires minimal maintenance. Furthermore, a number of fluid outlets may be provided, either to enable a number of different fluids to be pumped, or to increase the volume of a single fluid which is pumped.

Where such a device is provided with more than one outlet, adjacent outlets are preferably disposed around the inside circumference of that portion of the shroud having a minimum diameter. Such an arrangement ensures that the flow of fluid out of each outlet is maximised.

The shroud may be in the form of a convergent/divergent nozzle, the propeller being aligned with a parallel section of the nozzle between the convergent/divergent section.

Preferably the location along the axis of the shroud of the or each outlet is such that the or each outlet is not within the circumferential area swept by the propeller blades. With an arrangement of this nature, any solid matter suspended in the fluid flowing through the fluid pipe and emerging from the outlet or outlets is prevented from impinging directly onto the rotating propeller and damaging it. Additionally, any cavitation effects caused by the rotation of the propeller in the surrounding water have a reduced effect on the flow of fluid at the outlet or outlets.

Conveniently the outlet section of the or each fluid pipe may be substantially perpendicular to the inside circumference of the nozzle. Such an arrangement ensures that the optimum flow of fluid out of the outlet(s) is maintained when the direction of rotation of the propeller is reversed.

A tank may be provided and connected to the fluid pipe between the inlet and outlet thereof. Such a tank may, for example, contain a filter to separate and retain components of the fluid entering the inlet of the fluid pipe which cannot be discharged directly overboard so that they may be emptied later.

The fluid to be pumped by the apparatus may be air. In such an arrangement, the apparatus may be used to provide forced ventilation of parts of the vessel, or to create a partial vacuum inside a tank to draw water into the tank for ballast, for example.

The fluid pipe may be provided with a non-return valve so that fluid is prevented from flowing from the outlet towards the inlet of the fluid pipe. The provision of a non-return valve prevents the reverse flow of fluid through the fluid pipe when the propeller is at rest, or the siphoning of fluid back through the fluid pipe where the inlet is located vertically below the outlet, particularly when the propeller is at rest.

Advantageously an auxiliary fluid pump may be provided in the fluid circuit to maintain fluid flow in the fluid circuit when the propeller is at rest.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side elevation in partial crosssection of a propeller device in accordance with the invention; Figure 2 is a front elevation of the propeller device of Figure 1; Figure 3 is a plan view of the propeller device of Figure 1; Figure 4 is a partial side elevation in crosssection of the propeller device, similar to Figure 1 but with the fluid pipe outlet removed from the area of the propeller; Figure 5 is a front elevation of a propeller device with two fluid pipes; Figure 6 is a plan view of the propeller device of Figure 5; Figure 7 is a schematic view of a propeller device in accordance with the invention for circulating water through a water-lubricated bearing.

Figure 8 is a schematic view of a device in accordance with the invention, for circulating engine cooling water; Figure 9 is a schematic view of a bilge pump for use with the apparatus.

Figure 10 is a schematic view of a bilge pump similar to Figure 9 but with a sludge container; and Figure 11 is a schematic view of a ballast tank for use with the device.

Referring to Figures 1,2, and 3 an underwater propeller assembly 2 comprises a substantially cylindrical open-ended shroud 4 having an internal surface which has successively convergent, parallel and divergent sections located coaxially with the axis of rotation of a propeller 6 (shown only in Figure 1). At the section 12 of minimum internal diameter of the shroud 4 is located the outlet 10 of a fluid pipe 8.

Upon rotation of the propeller 6, a drop in pressure is induced at the minimum internal diameter 12 of the shroud 4. This pressure drop at the outlet 10 causes fluid within the fluid pipe 8 to be drawn out of the outlet 10 in the direction indicated generally by the arrow A.

Referring now to Figure 4, the fluid pipe 8' is shown moved along the axis of rotation of the propeller 6 so that the outlet 8' remains at the section 12 of minimum internal diameter of the shroud 4' so that the outlet 10' is not within the circumferential area swept by the ends of the propeller 6. On rotation of the propeller to the flow of fluid through the fluid pipe 8' is, as shown by the arrow A, such that solid matter suspended in the fluid does not impinge on the propeller 6 thereby reducing the possibility of damaging the propeller.

Furthermore, any cavitation effects caused by the rotation of the propeller 6 through the surrounding water tend towards the axis of rotation of the propeller 6 as the propelled surrounding water moves away from the propeller 6, the outlet 10' is less affected by such cavitation effects.

Figures 5 and 6 show the arrangement of a propeller device 14 in accordance with the invention, where two fluid pipes 16,18 are provided. The outlets 20,22 of fluid pipes 16,18 are located on the inside circumference of the shroud 14 at its minimum diameter 12 and are separated by an angle cs suspended at the centre of cylindrical nozzle 14. Angle o; is preferably at least such that the fluid emerging from outlet 20 is not affected by the fluid emerging from outlet 22 and vice versa and may be in the region of 600 as shown in the Figures, or at any angle greater than 100, dependent on the diameter of the cylindrical nozzle 14.

Two fluid pipes 16,18 may be employed to provide a greater outflow of a single fluid, or to enable two different fluids to be pumped from the outlets 16,18.

Although only two fluid pipes 16,18 are shown, it is envisaged that the apparatus could incorporate as many as six fluid pipes arranged, for example, at 600 angles around the shroud 14, or more fluid pipes if the angle between each fluid pipe is less than 600.

Figure 7 shows the underwater propeller assembly 2 of Figure 1, adapted to circulate water about a waterlubricated bearing 34. The assembly 2 is mounted to the outside of the vessel 30. The inlet 32 of fluid pipe 8 is connected to the inboard side of the water-lubricated bearing 34, which is shown here as the bearing for the shaft of the propeller 6. On rotation of the propeller 6 to the flow of fluid from the outlet of the fluid pipe 8 draws surrounding water into the bearing 34 through the outboard end of the bearing generally indicated at 36, along bearing 34 and into inlet 32.

Whilst the propeller is rotating the bearing is lubricated by the flow of surrounding water therethrough. Such an arrangement permits at least part of the bearing 34 to be located inboard the vessel 30.

Figure 8 shows the underwater assembly 2 of Figure 1 adapted to provide engine cooling where the engine 40 is capable of using the surrounding water as a coolant. The inlet 32 of the fluid pipe 8 is connected to the engine 40 to receive hot engine coolant therefrom. A further fluid pipe 48 has its outlet 42 connected to the engine 40 and its inlet 44 connected to the outside of the vessel 30 such that surrounding water may flow from inlet 44 through fluid pipe 48 to inlet 42 and then through the engine 40 to the inlet 32 of fluid pipe 8, and thence out through outlet 10. The flow of water along this path acts to cool the engine 40 and is produced on rotation of the propeller as described above. A non-return valve 38 may be located in fluid pipe 8 so that water may only flow in the direction described above.A valve 46 may be provided in fluid pipe 48 to close off the supply of water to the engine which may be necessary when servicing the engine, for example. A filter (not shown) may be provided at the inlet 44 to prevent the ingress of large solid matter or other pollutants entering the fluid pipe 48 and damaging or blocking it, or the coolant passageways (not shown) inside the engine 40, or the fluid pipe 8.

Figure 9 shows the apparatus adapted for use as a bilge pump. Fluid pipe 8 has its inlet 10 located in the bilges (ire. at the lowest point) of the inside of the vessel 30. On rotation of the propeller in the propeller assembly (not shown) as described above, unwanted fluid in the bilges is drawn into the inlet 10 and expelled overboard. A non-return valve 50 is preferably provided in fluid pipe 8 to prevent flooding of the vessel 30 or siphoning of surrounding water into the vessel 30 when the propeller is at rest.

The inlet 10 of the fluid pipe 8 may be connected to a container 52 to which is also connected the outlet 56 of a further fluid pipe 54 having its inlet 58 located in the bilges as shown in Figure 10.

The container may separate and retain components of the fluids drawn out of the bilges which it would be undesirable to pump directly overboard, for example oil, by means of suitable filters. The contents of container 52 may be emptied or otherwise disposed of at an appropriate later time. A non-return valve (not shown) may be located in fluid pipe 8 for the reasons given above.

Figure 11 shows the apparatus adapted for use as a ballast pump. Upon operation of the underwater propeller assembly (not shown) air is drawn into the outlet 10 of the fluid pipe 8 creating a partial vacuum within the ballast tank 60. A further fluid pipe 62 has its outlet 64 located inside the ballast tank, which is sealed apart from outlets 10,64 and the inlet 66 of fluid pipe 62 is located outboard beneath the surface of the surrounding water 68. The partial vacuum created in the ballast tank 60 draws in surrounding water from outside the vessel, thereby ballasting the vessel. Nonreturn valves (not shown) may be provided in the fluid pipes 8,62 and the fluid pipe 62 may be provided with a filter (not shown).

Claims (10)

1. A device for pumping fluid in propeller driven craft comprising a substantially cylindrical open-ended shroud surrounding and coaxially aligned with the propeller, the internal diameter of the shroud varying along the length thereof and at least one fluid pipe having its outlet located on the internal surface of the shroud at the region thereof with minimum internal diameter so that the negative pressure induced in the region on rotation of the propeller produces a pressure drop at the outlet of the or each fluid pipe.

2. A device as claimed in Claim 1, having a plurality of fluid pipes, the outlets of which are spaced circumferentially around the region of minimum internal diameter.

3. A device as claimed in Claim 2, wherein adjacent outlets are positioned such that they are separated by an angle of at least 60".

4. A device as claimed in any preceding Claim, wherein the location along the axis of the shroud of the or each outlet is outside the circumferential area swept by the propeller blades.

5. A device as claimed in any preceding Claim, wherein the outlet section of the or each fluid pipe is substantially perpendicular to the internal surface of the shroud at the point where it is located.

6. A device as claimed in any preceding Claim, including a tank connected in the fluid pipe(s) between the outlet and inlet thereof.

7. A device as claimed in any preceding Claim, wherein the fluid pipe(s) is provided with a non-return valve operable to prevent the flow of fluid from the outlet thereof towards the inlet thereof.

8. A device as claimed in any preceding Claim, wherein an auxiliary fluid pump is provided to produce fluid flow along the or each fluid pipe to the outlet thereof.

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9. A device as claimed in any preceding Claim, wherein the shroud is in the form of a convergent/divergent nozzle having a parallel section between the convergent and divergent sections, which parallel section is aligned with the propeller.

10. A device substantially as hereinbefore described and illustrated in the accompanying drawings.

10. A device substantially as hereinbefore described and illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows 1. A device for pumping fluid in propeller driven craft comprising a substantially cylindrical open-ended shroud surrounding and coaxially aligned with the propeller, the internal diameter of the shroud varying along the length thereof and at least one fluid pipe having its inlet located within the craft in communication with fluid to be pumped therefrom and its outlet located on the internal surface of the shroud at the region thereof with minimum internal diameter so that the negative pressure induced in the region on rotation of the propeller produces a pressure drop at the outlet of the or each fluid pipe.

2. A device as claimed in Claim 1, having a plurality of fluid pipes, the outlets of which are spaced circumferentially around the region of minimum internal diameter.

3. A device as claimed in Claim 2, wherein adjacent outlets are positioned such that they are separated by an angle of at least 60".

4. A device as claimed in any preceding Claim, wherein the location along the axis of the shroud of the or each outlet is outside the circumferential area swept by the propeller blades.

5. A device as claimed in any preceding Claim, wherein the outlet section of the or each fluid pipe is substantially perpendicular to the internal surface of the shroud at the point where it is located.

6. A device as claimed in any preceding Claim, including a tank connected in the fluid pipe(s) between the outlet and inlet thereof.

7. A device as claimed in any preceding Claim, wherein the fluid pipe(s) is provided with a non-return valve operable to prevent the flow of fluid from the outlet thereof towards the inlet thereof.

8. A device as claimed in any preceding Claim, wherein an auxiliary fluid pump is provided to produce fluid flow along the or each fluid pipe to the outlet thereof.

9. A device as claimed in any preceding Claim, wherein the shroud is in the form of a convergent/divergent nozzle having a parallel section between the convergent and divergent sections, which parallel section is aligned with the propeller.