This again shows a device comprising the body 1, blade 3 and fixed mount 4 installed in a pipe 2. In this case, however, there are stacks of piezoelectric discs 12 disposed on opposite sides of the blade 3 in parallel to the pipe 15 2. An elliptical spring metal ring 13 surrounds each piezoelectric stack 12 with the respective stack extending along the longer axis of the respective ellipse and firmly attached thereto at its opposite ends. In this case, however, the body 1 is permanently magnetised with poles along its upper and lower faces, (in the orientation of the pipe 2 shown in the Figure), and rectangularly-wound coils 14 5 attached to the walls of the pipe 2 are juxtaposed to these faces so that as the body oscillates and partially penetrates into and out of each coil pulses of electricity will be alternately induced. Facing each side of this magnetic stack are multi-limbed magnetically-permeable cores 20 wound with coils 21. In use of this device, as the body 1 oscillates the magnetic 10 stack 19 is impelled to repeatedly shuttle from one end of the chamber 16 to the other, with the consequence that with each excursion of the stack the polarity of the portion of it which faces each limb of a core 20 reverses.
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An alternative configuration utilising magnetic induction for power conversion, and which addresses this problem by shielding the magnetic 15 element from the flow, is shown in Figure 7. Within the body 1 in this case a bar-like permanent magnet 15 is trapped in a chamber 16 extending crosswise to the axis of the body but with freedom to slide therein so that as the body oscillates in use of the device, (up and down in the orientation shown in the Figure), the magnet is impelled to repeatedly shuttle from one end of the chamber to the other, by virtue its own 20 inertia.
Dolor Sordo Costado Derecho
35 It is observed that in use of the embodiment of Figure 4 the cylindrical piezoelectric stacks 10 will also tend to shed a Karman vortex trail within the flow of fluid passing through pipe 2, and at right angles to the trail shed from the body 1. Since the blade WO 2007/071975 PCT/GB2006/004777 7 3 is stiff in the direction of the dynamic loading induced by the vortices from the stacks 10, however, this phenomenon should not interfere with the essentially uniplanar oscillation of the body1 and blade 3. 5 Since the electrical output of a piezoelectric material is generally proportional to the level of induced stress but such materials exhibit relatively small strain rates even under high forces, it may be advantageous in a device according to the invention, which utilises piezoelectric energy conversion, to employ some form of mechanical linkage between the oscillating body/support system and the piezoelectric material 10 which converts the relatively high displacement/low force motion of the former to a relatively low displacement/high force action applied to the latter.
The means for converting the oscillatory motion ‘of the body and/or support means into electrical energy may be based on any suitable electrodynamic generation 10 method, including magnetic induction or the application of electrostrictive, magnetostrictive or piezoelectric materials to the body/support system. It follows that a frequency equivalent to the particular natural frequency of the respective body/support system can be included in the trails produced by the interaction of that body with a range of different flow velocities. 20 Figure 4 illustrates a further variant of the devices described above where, as an alternative or in addition to the piezoelectric material 5, 6 or 9, stacks of piezoelectric discs 10 are mounted on the body 1 crosswise to its own axis (above and below the body in the orientation shown in the Figure), with masses 11 fixed to the free end of each stack. Features of the present invention will now be more particularly described, by way of example, with reference to the accompanying schematic drawings, in which: 30 Figure 1 is a longitudinal section through one embodiment of a power harvesting device according to the invention, installed in a pipe; Figures 2 and 3 illustrate variants of the device of Figure 1; 35 Figure 4 is an end view of a further variant of the device of Figure 1, installed in a pipe; WO 2007/071975 PCT/GB2006/004777 4 Figure 5 is a side view of another embodiment of a power harvesting device according to the invention including a force-amplifying mechanism, installed in a pipe; Figure 6 is a side view of a further embodiment of a power harvesting device 5 according to the invention, installed in a pipe; Figure 7 is a side view schematically illustrating the interior of a further embodiment of a power harvesting device according to the invention; 10 Figure 8 is a pictorial view of a variant of the device of Figure 7 installed in a pipe, with the pipe largely broken away; Figure 9 is a side view schematically illustrating the interior of another variant of the device of Figure 7; 15 Figures 10 and 11 are schematic sections through fittings comprising several devices according to the invention; and Figure 12 is a pictorial -view of a pair of devices according to a further embodiment of 20 the invention installed in a pipe, with the pipe largely broken away.
Dolor Espalda Cáncer Pulmón
In this respect the body 1 is carried at the end of a blade 3 of e.g. Que tomar para dolor muscular . If necessary to prevent the piezoelectric material becoming overstrained and risking fracture, stops 30 may be incorporated in the design to limit the displacement of the body 1 and consequent flexure of the blade 3. Figures 2 and 3 illustrate variants of the structure of the device shown in Figure 1. 35 In Figure 2, instead of the thin piezoelectric patches 5 along the length of the blade 3, relatively high volume piezoelectric elements 6 are located between the fixed mount WO 2007/071975 PCT/GB2006/004777 6 4 and the blade 3 at its root, which is the most highly stressed region of the device when the body 1 oscillates. WO 2007/071975 PCT/GB2006/004777 10 Figure 11 illustrates a divergent-convergent fitting 26 similar to the fitting 22 with a central section of increased diameter as compared to the pipe lengths 23 and 24 to which it is fitted and in which four power harvesting devices comprising bodies 1 and cantilever arms 3 are supported from two fixed mounts 4 extending chordwise of the 5 fitting.
WO 2007/071975 PCT/GB2006/004777 1 GENERATION OF ELECTRICAL POWER FROM FLUID FLOWS, PARTICULARLY IN OIL OR GAS WELL PIPES The present invention relates to the generation of electrical power from fluid flows. Depending on the prevailing conditions and the type and location of the well, flows 20 may be encountered comprising oil, gas, water, steam or mixtures of the same in multiple phases. This variant avoids the separate annular passage 26 which might present a risk of clogging in particularly contaminated flows.
Powering this 10 equipment through conductors from the surface is difficult and expensive, in view of the very long lengths of cabling that may be required and the aggressive conditions which exist downhole, where breakage or damage to the conductors or their insulation at some point along their length is a serious risk. In this example a fitting 22 is installed between two pipe lengths 23 and 24. The fitting 22 has a central passage 25 of similar bore to the pipes 23/24, surrounded by an annular 30 passage 26 through which a proportion of the flow passing into the fitting is diverted as indicated by the arrows in the Figure. It is also 25 desirable in some circumstances that the bore of downhole pipes is left unobstructed to permit the passage of tools or instrumentation through the system.