Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
  • H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
  • H02N2/18—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing electrical output from mechanical input, e.g. generators
  • H02N2/185—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing electrical output from mechanical input, e.g. generators using fluid streams

Definitions

• This invention relates to a piezoelectric fluid-electric generator, and more particularly to such a generator which ' 5 includes means for driving a piezoelectric bending element to oscillate with the energy of the fluid stream.
• the invention results from the realization that oscil ⁇ lation of a piezoelectric bending element can be induced by using the elastic restoring force of the piezoelectric bending element to respond to deforming forces applied by a fluid flow causing the piezoelectric bending element to flutter or oscillate and generate electric power.
• This invention features a piezoelectric fluid-electric generator including a piezoelectric bending element and means for mounting one end of the bending element in a fluid stream. There are means for driving the piezoelectric bending element to oscillate with the energy of the fluid stream. Electrode means connected to the piezoelectric bending element conduct current generated by the oscillatory motion of the piezoelectric bending element.
• the piezoelectric fluid-electric generator is an elongate member.
• the means for driving may include a vane mounted to the free end of the piezoelectric bending element, and the vane may be an integral extension of the piezoelectric bending element.
• the means for driving alternately may include duct means for increasing the flow velocity of the fluid directed at the surface of the piezo ⁇ electric bending element to reduce the pressure in that region and draw the piezoelectric bending element toward
• the generator may also include funnel means for focussing the fluid flow to the piezoelectric bending element.
• the fluid which drives the generator may be air, and the generator may function as a windmill, or the fluid may be liquid, such as water. In a preferred embodiment, a number of such generators are used, for example in a windmill configuration, to convert wind energy to electric power.
• Fig. 1 is an axonometric view of a piezoelectric fluid- electric flutter vane generator according to this invention
• Fig. 2 is a schematic view showing the streamlines of fluid flow about the fluid-electric flutter vane generator of Fig. 1;
• Figs. 3 and 4 are a side, elevational and top plan views, respectively, showing various dimensions of a specific flutter vane generator configuration according to this invention
• Fig. 5 is an axonometric view of a portion of a snow fence with flutter vane generators mounted thereon;
• Fig. 6 is an axonometric view of an alternative type of piezoelectric fluid-electric reed generator according to this invention mounted over a fluid duct which directs the fluid directly at the piezoelectric bending element;
• Fig. 7 is a schematic diagram showing the stream lines associated with fluid flow around the reed generator of Fig. 6;
• Fig. 8 is an axonometric view of a windmill having funneling surfaces to enhance the wind flow to a group of reed generators similar to those shown in Fig. 6;
• Fig. 9 is a portion of a rail fence containing a plurality of reed generators.
• Fig. 10 is a schematic diagram of a plurality of piezoelectric fluid-electric generators according to this invention with their electrodes connected through diodes to a power bus.
• the invention may be accomplished by a piezoelectric fluid-electric generator which produces oscillation in a piezoelectric bending element to generate electric power from fluid power.
• a piezoelectric fluid-electric generator which produces oscillation in a piezoelectric bending element to generate electric power from fluid power.
• aerodynamic oscillation may be produced from wind power, and a group of piezoelectric fluid-electric generators may be used to function as a windmill.
• Other fluids for example water, may be used also.
• a flutter vane type of piezo ⁇ electric fluid-electric generator in which an enlarged vane may be positioned at the free end of a piezoelectric bending element to improve the aerodynamic oscillation in the windstream as the air stream flows along the vane.
• a reed-type piezoelectric fluid-electric generator associated with a duct which directs the airstream directly at the bending element and which restricts the flow of the air stream and locally increases the velocity to create a suction, according to Bernoulli's Principle, on one side of the piezoelectric bending element until the elastic restoring force of the bending element overcomes the suction and causes the reed to bend in the opposite direction.
• an enlarged vane added to the free end of the piezoelectric bending element may be a separate material fastened or bonded to the piezoelectric bending element, or it may be an integral continuation of the piezoelectric bending element enlarged to provide the extra surface area to improve the fluttering action.
• a piezoelectric fluid-electric generator 10 of the flutter vane type 12 including a piezoelectric bending element 14 and a vane 16 held b .U- shaped member 18, fastened to the free end 20 of element 14.
• the other end of element 14 is held in a support in a mounting device, channel 22.
• Element 14 includes two piezoelectric portions 24, with an elastic sheet metal member 28 between them. Electrodes 30, 32 are attached to the piezoelectric members 24, 26, respectively. Air flows along vane 16 in the direction shown by arrows 34, as more clearly indicated in Fig. 2, where the stream lines 36 flowing over the fluttering element 14, shown here without vane 16, shed vortices 38 from the trailing edge of the element 14.
• the shedding vortices produce low pressure in that region, which sucks the vane to one side, as indicated in Fig. 2.
• element 14 starts to move in the opposite direction, where a vortex vacuum is beginning to build up due to curvature. This action continues so that the element 14 flutters back and forth, generating an alternating electric current which is conducted to a load through electrodes 30, 32. Vane 16 enhances the aerodynamic oscillation or flutter.
• a typical flutter vane. Fig " . 3 may include a 0.254 cm. thick Mylar vane 16a, Fig. 3, which is 2.54 cms. by 2.22 cm. and is bonded with a 0.635 cm. overlap to the end of a 0.05 cm. thick piezoelectric bending element 14a, which is 0.80 cm. wide and 3.81 cms. long made of Gulton ceramic type G-1195 with an incidence angle of + or -30° as indicated in Fig. 4.
• a wind velocity of 40 kilometers/hour produces a peak-to-peak deflection of 0.318 cm. at the tip and the bending element produces an electrical output of 0.833 milliwatts.
• a plurality of flutter vane 12 piezoelectric fluid-electric generators may be arranged, for example.
• piezoelectric fluid-electric generator 10b may include a reed 12b generator, which includes a piezoelectric bending element 14b having one end fixed by screw 60 to mounting block 62 on plate 6 , so that the free end 20b is positioned over duct or hole 66 in plate 64.
• Air flow 34b or other fluid flow directed against the surface of piezoelectric bending element 14b is shown in detail in Fig. 7, where stream lines 36b pass around the reed-type bending element 14b.
• the higher flow velocity of the air stream as it moves through hole or duct 66 and around bending element 14b produces a localized region of low pressure which, as explained by Bernoulli's Principle, sucks element 14b, toward plate 64, thereby decreasing the flow.
• the suction force decreases until the elastic force of bending element 14b reverses the downward motion and allows the flow velocity of the air stream to once again increase as bending element 14 moves upward until once again the suction force overcomes the elastic force and then element 14b moves downward and the oscillation cycle repeats.
• a group of piezoelectric fluid-electric generator reeds 12b may be mounted on channel mast 70, Fig. 8, which is rotatably attached by a bearing not shown to mounting post 72 so that the funneling sur aces 74, 76 may be always rotated into the wind by the action of weathervane 78.
• Each of the generator reeds 12b is mounted, as shown in Fig. 6, with its free end 20b over a duct or hole 66, not visible in Fig. 8.
• a group of such generator reeds 12b may be mounted over similar holes or ducts on the rails 90, 92, of a common highway rail fence 94, as shown in Fig. 9, with their free ends mounted over ducts or holes not visible in Fig. 9.
• the piezoelectric fluid-electric generators 12b may be connected to full-wave rectifier diode bridge 100 , whose DC output is then supplied on bus 102 to a load.

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• Wind Motors (AREA)
• Endoscopes (AREA)
• General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

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• 1983
  • 1983-06-03 WO PCT/US1983/000901 patent/WO1984005010A1/en active Application Filing
  • 1983-06-03 EP EP19830902345 patent/EP0147391A1/de not_active Withdrawn
  • 1983-06-03 GB GB08502536A patent/GB2152767B/en not_active Expired
  • 1983-06-03 DE DE19833390497 patent/DE3390497C2/de not_active Expired
  • 1983-06-03 JP JP50238183A patent/JPS60501238A/ja active Pending

Non-Patent Citations (1)

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