GB2384031A

GB2384031A - Flexible beam with pumping means

Info

Publication number: GB2384031A
Application number: GB0200452A
Authority: GB
Inventors: Francis James Macdonald Farley
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-17
Filing date: 2002-01-10
Publication date: 2003-07-16
Also published as: GB0200452D0; GB0124896D0

Abstract

A flexible beam comprises two parallel lines, of rigid panels 1 - 5, separated by and attached to an elastic medium 11. The joints or gaps 6 - 10 between the panels in one line are positioned opposite the centres of the panels in the other line. The beam incorporates a pumping means to pump fluid when the beam is flexed. The pumping means may comprise cavities 12 - 14 which are alternately compressed or expanded when the beam is flexed. The pumping means may also be mechanical pumps connected between the panels in one line and the panels in the other and driven by the flexing of the beam. The pump may be driven by water waves.

Description

FLEXIBLE BEAM WITH PUMPING MEANS The invention relates to a mechanical beam which pumps water or other fluid when it is flexed. It is particularly adapted to extracting energy from water waves.

A flexible beam floating on the sea with its long axis parallel to the direction of wave propagation will be flexed vertically by the action of the waves (see for example reference 1) To extract energy it should be arranged that the flexing of the beam causes water or other fluid to be pumped to a useful output. This invention provides a flexible beam incorporating pumping means together with restoring forces tending to keep the beam straight. For clarity it is convenient to describe the invention as a beam oriented horizontally but the beam can be used in any orientation According to this invention in its first characteristic the flexible beam comprises two parallel horizontal lines of rigid panels with the joints or gaps in each line located above or below the centre of a panel in the opposite line In each line the rigid panels are collinear and neighbouring panels abut each other end to end with a small gap between them. They may be attached to each other by hinges or flexible joints, or located by their attachment to a panel in the opposite line. The rigid panels in each line may be of any suitable shape and may have a complex structure. According to the invention in its second characteristic each panel in one line is attached to an elastic medium which is in turn attached to a panel in the opposite line.

The elastic medium may be continuous or in discrete sections and may contain cavities filled with air or water. Cavities containing air under pressure increase the rigidity of the beam.

Cavities containing water or other fluid can be used for pumping. It results that when the beam is flexed vertically the distance between a joint or gap in one line and the opposite panel in the other line is modified, increasing or decreasing according to the position of the joint or gap and the direction in which the beam is flexed. According to this invention in its third characteristic these changes of distance may be used to pump fluid, either by driving a conventional pump or by compressing cavities in the elastic medium.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in lateral cross section at the centre line a portion of an embodiment of the flexible beam.

Figure 2 shows in lateral cross section at the centre line the same portion of this flexible beam when it is bent Figure 3 shows in lateral cross section a portion of the flexible beam illustrating an embodiment with a conventional piston pump.

Figure 4 shows in lateral cross section a portion of the flexible beam illustrating an embodiment in which the cavities in the elastic medium are used to pump fluid.

Figure 5 shows in plan the cross section in the median plane of a portion of the flexible beam illustrating an embodiment in which the cavities in the elastic medium are used to pump fluid with inlet and outlet manifolds running inside the elastic medium.

Figure 6 shows in plan the cross section in the median plane of a portion of the flexible beam illustrating an embodiment in which fluid is pumped progressively from one cavity in the elastic medium to another along the length of the beam Figure 7 shows a cross section in mid-plane elevation of another embodiment together with a plan view as seen from the broken line XX A particular embodiment of the invention will now be described with reference to Figure 1 which shows part of the embodiment in lateral elevation as a cross section at the centre line The upper layer comprises a series of rigid panels of which two panels 1 and 2 are illustrated, the panels being attached to each other by hinges or flexible joints illustrated at 6,7 and 8 The lower layer is essentially similar with panels 3,4 and 5 connected by the hinges or flexible joints 9 and 10; hinge 7 in the upper layer is located opposite the centre of panel 4 in the lower layer, and so on, with the effect that each joint is located more or less exactly opposite the centre of a panel in the other layer. The layers are attached to and separated by a solid elastic medium 11 which may for example be made of synthetic rubber. The elasticity of the medium 11 tends to keep the beam straight The elastic medium 11 contains cavities 12,13 and 14. Cavities containing air under pressure increase the rigidity of the beam Cavities containing water or other fluid can be used for pumping.

When the beam is flexed or bent by an external couple as illustrated in Figure 2, the distance between each upper joint 6,7, 8 and the corresponding closest lower panel 3,4, 5 increases, while the distance between each lower joint 9,10 and the corresponding upper panel 1,2 decreases. If the beam is flexed in the opposite direction these changes are reversed The change in distance between a joint and its corresponding opposite panel may be used directly in one embodiment to actuate a pump as shown in Figure 3 in which by way of example a pump body 19 is mounted on panel 4 and actuated by a push rod 20 connected to joint 7. (For clarity the elastic medium between the layers is not shown in this Figure, and by way of illustration in this embodiment the shape of panel 4 and the flexible joint 7 are of different design from those illustrated in Figure 1, but their functions are the same) In the embodiment illustrated in Figures 1 and 2, cavities 12,13, 14 are included in the elastic medium 11. Then when the beam is flexed as illustrated in Figure 2, the volume inside cavities 12 and 14 is reduced, while the volume inside cavity 13 is increased. These changes of volume can be used in various ways to pump water or other fluid.

In the first method, illustrated by way of example in Figure 4, one way valves 21 and 22 are installed in the rigid panel 4 so that water (or other fluid) enters cavity 13 via valve 21 and is pumped to an output manifold (not illustrated) via valve 22.

In the second method, illustrated as an example of another embodiment in the plan view Figure 5, inlet and outlet manifolds 23,24 running the length of the beam are incorporated within the elastic medium 11 and fluid is pumped via one way valves 25 and 26 from the inlet manifold 23 into cavity 13 and then out to the outlet manifold 24, and likewise for the other pumping cavities.

In the third method, illustrated as an example of another embodiment in the plan view Figure 6, one way valves 27 and 28 are installed between the cavities 12,13, 14 with the effect that

water or other fluid is pumped successively from cavity 12 to cavity 13, from 13 to 14 and so on from one end of the beam to the other, finally being pumped out to a useful destination With this method a higher final pressure may be achieved.

The rigid panels in each layer may be of any suitable shape, for example thickened at the centre, to resist mechanical forces according to the art of mechanical design, as illustrated in Figure 3, or of complex structure. Likewise the hinges or flexible joints can be of any suitable design or alternatively the rigid panels may be simply held in their correct relative positions by means of their common attachment to the elastic medium 11.

In another embodiment illustrated in Figure 7 the horizontal panels in each layer are of complex shape and the discontinuous elastic medium is concentrated at the most useful locations. Except at the ends, each panel in the beam is identical but the panels in the upper layer are inverted relative to those in the lower layer. The panels in this embodiment will now be described in further detail with reference to Figure 7 which shows a portion of the flexible beam in lateral elevation of the mid-plane section and the view from the broken line XX in plan. For clarity in Figure 7 the panel in the lower layer is hatched while the panels in the upper layer are not hatched; the elastic medium has closer hatching lines. At the centre of each panel 29 there is a vertical extension in the form of a rectangular box with sides 30 and roof 31 but open at the ends, reinforced by the central vertical sheet 41. (This extension will for ease of reference be called the"slot"). At the end of each panel and rigidly attached to it there are thin horizontal tongues 32. It is arranged that the tongues of the panels in the upper layer fit closely inside the slots of panels in the lower layer, and vice versa. The tongues 32 are free to slide vertically inside the slots but are constrained horizontally by the vertical sides 30. The elastic medium 33 which connects the upper and lower layers is located inside the slots, above and below the tongues 32, and in its equilibrium position holds the tongues vertically in the centre of the slots, thus ensuring that the flexible beam is maintained straight But when the beam is bent by external forces, the tongues move vertically inside the slots, compressing or expanding parts of the elastic medium and generating restoring forces to resist the bending. In this embodiment the elastic medium 33 may with advantage contain spaces 34 which are filled with gas under pressure so as to increase the overall rigidity of the beam In this embodiment the tongues 32 fit closely between the vertical sides 30 of the slots with the effect that the panels in the upper layer are precisely aligned laterally with respect to the panels in the lower layer: no lateral movement is available with the effect that the beam cannot flex laterally. However the tongues 32 can slide vertically between the sides 30 of the slots with the effect that the beam can flex in the vertical plane its overall rigidity being determined by the elastic medium 33. Roller bearings may with advantage be incorporated between the tongues 32 and the sides 30 of the slots.

In this embodiment further sections of elastic medium may be incorporated as illustrated at 35 in Figure 7. These sections may include spaces 36 filled with water with the effect that the flexing of the beam causes water to be pumped at high pressure through one way valves to a useful output, generally as described above.

In this embodiment a longitudinal compressive force is applied to the beam as a whole by means of lateral cables under tension which are connected between rigid arms projecting from the two ends of the beam. The panels in the upper layer are not connected to each other by hinges but are located longitudinally with respect to the neighbouring panels in the lower layer

via the cylindrical rollers 37,38, 39,40 in Figure 7. In the presence of the longitudinal compressive force, each upper panel is pressed against a roller which in turn presses against a lower panel and each lower panel is pressed against a roller which in turn presses against an upper panel and so on along the length of the beam. The rollers hold the panels in position longitudinally but allow relative motion in the vertical plane in rotation and position. The rollers may be continuous across the beam as illustrated at 37 or with advantage be divided into separate sections as illustrated at 38,39, 40, with the effect that the panels are free to twist relative to each other, this twist however being resisted by the elastic medium 33, and this twist may be used to pump water.

It may be noted that in this embodiment of the flexible beam the location of the panels relative to each other is achieved by several independent means. Laterally the panels are located by means of the tongues 32 which slide inside the vertical sides 30 of the slots. Vertically they are located by the elastic medium 33 above and below the tongues 32. Longitudinally they are located by the rollers 37,38, 39,40. This separation of function implies a corresponding separation of forces and allows more flexibility and economy in the mechanical design of each means.

In this embodiment the shape of the panels may with advantage be modified so that the tongues 32 of the panels of the lower layer are at the same horizontal level as the tongues 32 of the panels of the upper layer.

In an alternative version of this embodiment, not illustrated, the rollers separating the panels of the upper layer from those of the lower layer may be replaced by ball and socket joints.

In any of the embodiments described above, the elastic medium may be consist of any material (or combination of materials) which withstands linear compression and expansion and supplies a restoring force tending to return the material to its original configuration. By way of example without limitation the elastic medium may be a mechanical spring, an elastomer, an elastomer with metal reinforcement, a piston and cylinder filled with air or gas under pressure with any form of seal including sliding or rolling seals, a corrugated tube made of metal or elastomer with or without metal reinforcement, etc.

The flexible beam with pumping means may be used as part of an ocean wave energy converter, as proposed for example in reference 1. With any of the pumping means described above, if the beam is floating on the sea and flexed by the action of the waves, power will be absorbed from the waves and converted to useful hydraulic power.

Reference 1: F. J. M. Parley, Applied Ocean Research, Vol 4,1982, pages 57-63

Claims

CLAIMS 1 A flexible beam comprising two parallel lines of rigid panels separated by and attached to an elastic medium with the joints or gaps between the panels in one line located opposite the centres of the panels in the other line and incorporating pumping means to pump fluid when the beam is flexed.
2. A flexible beam as claimed in claim 1 in which the pumping means comprises cavities inside the elastic medium which are alternately compressed and expanded when the beam is flexed with the effect that fluid is pumped in and out of the cavities via one way valves.
3 A flexible beam as claimed in claim 1 in which the pumping means comprises mechanical pumps connected between the panels in one line and the panels in the other line, driven by the flexing of the beam.
4 A flexible beam as claimed in claims 1,2 or 3 with cavities inside the elastic medium which are filled with air under pressure to increase the rigidity of the beam
5 A flexible beam as claimed in claims 1 or 2 in which parts of the panels in one line fit into vertical slots in the panels in the other line with the effect that the panels are located laterally relative to each other.
6 A flexible beam as claimed in claims 1,2 or 3 in which the panels in one line are located longitudinally relative to the panels in the other line by rollers between the panels
7 A flexible beam as claimed in claims 1,2 or 3 in which the panels in one line are located longitudinally relative to the panels in the other line by ball and socket joints between the panels
8 A flexible beam as claimed in claims 6 or 7 with lateral cables under tension connecting the two ends of the beam.
9. A flexible beam as claimed in claims 1,2, 3,4, 5,6, 7 or 8 used for converting the energy of water waves into hydraulic power
10. A flexible beam with pumping means substantially as described