CARPET FOR ELECTRICITY GENERATION

Description

BACKGROUND1. FIELD

[0001] The disclosure of the present patent application relates to alternative energy sources, and particularly to an electrical power generating carpet that generates electricity when the carpet is walked upon.2. DESCRIPTION OF THE RELATED ART

[0002] Global energy consumption is increasing at an exponential rate due to an ever-increasing human population, coupled with both basic human needs and a continually increasing reliance on electricity and machinery. Energy production from traditional resources (e.g., coal, water, wind, etc.) and newer renewable resources (e.g., solar, geothermal, etc.) is not sufficient to meet global energy demands. In addition, electrical energy produced from fossil-fuel or nuclear power sources present environmental hazards from greenhouse emissions and the disposal of hazardous waste. Although numerous attempts have been made to recover energy from human action itself, from bicycle-powered generators to shoes and clothing with embedded generators, none of these attempts have been entirely successful.

[0003] EP 3 121 950 A1 describes an energy harvesting flooring material comprising a layer of synthetic material, an energy harvesting layer and a layer of conductive material; and an energy harvesting system comprising the energy harvesting flooring material, a rectifier and an electrical storage device. There is no disclosure of piezoelectric stripes or an embedded tile in EP 3 121 950 A1. The same applies with respect to the disclosure of JP 2011-153469 A. Further devices of the prior art are described by CN 102409833 A, JP 2015-21240 A, WO 2013 / 132441 A1, JP 2010-63321 A and CN 205444795 U. Documents CN104983279A, CN104643860A, CN206197698U disclose carpets with embedded piezoelectric generators, but no tiles as defined by the independent claims.

[0004] Thus, an electrical power generating carpet solving the aforementioned problems is desired.SUMMARY

[0005] The invention is defined by the features of the independent claims. Preferred embodiments are defined by the features of the dependent claims.

[0006] The electrical power generating carpet is a carpet having piezoelectric-based electrical power generating tiles embedded therein. At least one of the energy generating tiles is embedded or otherwise integrated in the carpet, which may be any suitable type of flexible carpet or floor covering, such as moquette carpeting or the like. Preferably, a plurality of the electrical power generating tiles are embedded in the carpet. Each energy generating tile includes upper and lower plates having opposed top and bottom surfaces, at least one piezoelectric strip mounted on the top surface of the lower plate, and an engaging member attached to the bottom surface of the upper plate. The upper and lower plates are stacked such that the engaging member contacts the at least one piezoelectric strip.

[0007] The upper plate is preferably formed from a flexible material, such as flexible plastic, and the lower plate is preferably formed from a rigid material, such as a rigid plastic. In use, when a user steps on the carpet tile, the upper plate of the tile flexes, causing the engaging member thereof to apply mechanical stress to the piezoelectric strip, thereby generating electrical voltage in the piezoelectric material. When the user steps off the carpet tile, the mechanical stress is relieved, generating an electric current through the piezoelectric material. Preferably, each tile includes a plurality of piezoelectric strips electrically connected to one another in parallel. The plurality of piezoelectric strips are each oriented substantially parallel with respect to one another and the engaging member is oriented substantially orthogonal with respect to the plurality of piezoelectric strips, such that when the user steps on the carpet, the engaging member causes the stress to be evenly distributed across the plurality of piezoelectric strips. Preferably, a full-wave bridge rectifier is provided for each tile. The rectifiers produce a direct current output.

[0008] These and other features of the electrical power generating carpet will become readily apparent upon further review of the following specification and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a top view of an electrical power generating carpet, partially broken away to show tiles embedded therein. Fig. 2 is a perspective view of one of the tiles embedded in the electrical power generating carpet of Fig. 1, shown with the upper plate exploded from the lower plate. Fig. 3 is a bottom view of the upper plate of a tile of the electrical power generating carpet of Fig. 1. Fig. 4 is a side view in section of the tile of Fig. 2. Fig. 5 is a schematic diagram of a tile of Fig. 2 connected to a rectifier. Fig. 6 is a schematic diagram showing electrical connection of the tiles in the electrical power generating carpet of Fig. 1.

[0010] Similar reference characters denote corresponding features consistently throughout the attached drawings.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The electrical power generating carpet, referred to generally in the drawings as 10, is a carpet having piezoelectric-based electrical power generating tiles 14 embedded therein. As shown in Fig. 1, at least one of the energy generating tiles 14 is embedded or otherwise integrated in the external carpet material 12, which may be any suitable type of flexible carpet or floor covering, such as moquette carpeting or the like. Preferably, a plurality of tiles 14 are embedded in the carpet 12. As best seen in Fig. 2, each tile 14 includes a lower plate 20 having a bottom surface 21 and a top surface 23, and an upper plate 30 having a top surface 32 and a bottom surface 34. The upper plate 30 is preferably formed from a flexible material, such as flexible plastic, and the lower plate 20 is preferably formed from a rigid material, such as a rigid plastic.

[0012] It should be understood that the overall dimensions and configuration of the tile 14 shown in Fig. 2 are provided for exemplary purposes only. The overall number and size of tiles 14 will ultimately depend upon the particular flooring application and design of the overall carpet 10. A typical exemplary configuration for the lower plate 20 and the upper plate 30 is a square configuration with each side having a length of approximately twenty centimeters. For such exemplary dimensions, upper plate 30 would typically have a thickness of approximately two millimeters, and the lower plate 20 would typically have a thickness of approximately six millimeters. As noted above, the upper plate 30 is preferably flexible, and it should be understood that any suitable type of flexible and resilient material may be used. As an example, upper plate 30 may be formed from flexible plastic. An additional thin layer of aluminum may be adhered to the top surface 32 of upper plate 30 to provide additional protection for the upper plate 30 as users walk on the carpet 10.

[0013] As shown, at least one piezoelectric strip 24 is mounted on the top surface 23 of the lower plate 20. Preferably, as shown, a plurality of piezoelectric strips 24 are mounted on the top surface 23, although it should be understood that the three piezoelectric strips 24 are shown for exemplary purposes only, and that any suitable number of piezoelectric strips 24 may be used in each tile 14. As shown in Figs. 2 and 4, the piezoelectric strips 24 are not mounted directly on the top surface 23 of the lower plate 20, but are mounted on and extend across parallel spacers 26, 28 so that when a person steps on the tile 14, the piezoelectric strips 24 may bend slightly in the middle portion of the strips 24 between the two spacers 26, 28. The spacers 26, 28 may be formed from any suitable type of electrically nonconductive material, such as plastic or the like. Using the exemplary dimensions given above, the spacers 26, 28 may be rectangular and have a length of approximately fourteen centimeters, a width of approximately two centimeters, and a thickness of approximately two millimeters.

[0014] As best shown in Figs. 3 and 4, an engaging member 36 is attached to the bottom surface 34 of the upper plate 30. In each tile 14, the lower and upper plates 20, 30 are stacked on top of each other such that the engaging member 36 contacts the at least one piezoelectric strip 24, and when a person steps on the upper plate 30, the engaging member 36 bears against the middle portion of each piezoelectric strip 24, bending the strip 24 and inducing a voltage therein. When the person steps off the tile 14, the upper plate 30 resiliently returns to its neutral position, lifting the engaging member 36 with it to relieve the bending stress on the piezoelectric strip 24, inducing a current in the strip 24. Thus, the upper plate 30 acts as a pressure plate to apply pressure to the piezoelectric strips 24. Each piezoelectric strip 24 has a pair of leads 18A, 18B, and as noted above, each tile 14 preferably includes a plurality of piezoelectric strips 24. As shown in Figs. 2 and 5, piezoelectric strips 24 are preferably connected to one another in parallel (via their respective pairs of leads 18A, 18B), such that each tile 14 has a single pair of leads 16A, 16B. It should be understood that any suitable type of piezoelectric strips may be used. For example, piezoelectric strips may be D220-A4-503YB piezoelectric sensors or transducers manufactured by Piezo Systems, Inc. of Woburn, MA.

[0015] In use, when a user steps on the carpet 10, the upper plate 30 of one or more tiles 14 flexes, causing the engaging member 36 thereof to apply a bending force to the piezoelectric strip(s) that it bears against 24 to generate an electrical potential across leads 16A, 16B. In the preferred embodiment of Figs. 2-4, in which a plurality of piezoelectric strips 24 are provided, the plurality of piezoelectric strips 24 are each oriented substantially parallel with respect to one another and the engaging member 36 is oriented substantially orthogonal with respect to the plurality of piezoelectric strips 24. Thus, when the user steps on the carpet 10, the engaging member 36 causes the bending stress to be evenly distributed across the plurality of piezoelectric strips 24. Using the exemplary configuration described above, the engaging member 36 may be substantially rectangular, having a length of approximately twelve centimeters, a width of approximately one centimeter, and a thickness of approximately two millimeters. The engaging member 36 may be formed from any suitable type of electrically nonconductive material, such as flexible plastic or the like. As shown in Figs. 2 and 4, a pair of laterally disposed spacers 22 may also be attached to the top surface 23 of the lower plate 20. The side spacers 22 support the upper plate 30 with sufficient thickness to compensate for the engaging member 36, piezoelectric strips 24 and spacers 26, 28 sandwiched between the upper plate 30 and the lower plate 20. Using the exemplary dimensions given above, the spacers 22 may be substantially rectangular, having a length of approximately twenty centimeters, a width of approximately two centimeters, and a thickness of approximately two millimeters.

[0016] With regard to power generation, as shown in Fig. 5, a full-wave bridge rectifier is preferably provided for each tile 14. Each full-wave bridge rectifier is in electrical communication with the corresponding tile 14 for producing a direct current (DC) output. In Fig. 5, a conventional full-wave bridge rectifier (FWBR) circuit (optionally combined with a buck converter (BC) and its associated circuitry), identified generally as 40 in the drawings, is connected to the tile 14 to form a piezoelectric power generating unit 42, which outputs a DC current. As shown in Fig. 6, sub-groupings of multiple such power generating units 42 may be interconnected across corresponding capacitors C 4 , C 5 , ... C N (for N-3 such sub-groupings). Here, the first sub-grouping (connected across capacitor C4) produces the first potential V 01+ , and all N-3 sub-groupings contribute to the overall output voltage V OUT+ for the electrical power generating carpet 10.

[0017] Returning to Fig. 5, it should be understood that any suitable type of full-wave bridge rectifier (and associated circuitry) may be used. As an example, FWBR / BC 40 may be a LTC3588-1 nanopower energy harvesting power supply chip, manufactured by Linear Technology of Milpitas, CA. The LTC3588-1 chip has an energy harvesting circuit that integrates a full-wave bridge rectifier circuit with a high-efficiency buck converter circuit that regulates output of the rectifier circuit. Four output voltages (1.8 V, 2.5 V, 3.3 V and 3.6 V) are pin selectable with up to 100 mA of continuous output current. In the exemplary driver circuit of Fig. 5 associated with FWBR / BC 40, the storage capacitor C S may have a capacitance of 100 µF (rated at 16 V maximum), capacitor C 1 may have a capacitance of 1 µF (rated at 6 V maximum), capacitor C 2 may have a capacitance of 4.7 µF (rated at 6 V maximum), capacitor C 3 may have a capacitance of 47 µF (rated at 6 V maximum), and inductor I may have an inductance of 10 µH. The electrical power generated by the carpet may be used to power a load or used to recharge a battery or other electrical energy storage device.

[0018] It is to be understood that the electrical power generating carpet is not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.

Claims

1. An electrical power generating carpet (10), comprising a carpet (10) having at least one tile (14) embedded therein, the at least one tile (14) including: upper and lower plates (20, 30), each of the plates (20,30) having opposing top and bottom surfaces (21, 23, 32, 34), the upper plate (30) being flexible and resilient, the upper plate (30) being disposed on top of the lower plate (20); at least one elongated piezoelectric strip (24) mounted on the top surface of the lower plate (20); and an engaging member (36) attached to the bottom surface of the upper plate (30) and bearing across the at least one elongated piezoelectric strip (24) between opposing ends of the strip (24) so that when a person steps on the at least one tile (14), the upper plate (30) flexes and the engaging member (36) exerts a bending stress on the at least one elongated piezoelectric strip (24), inducing a voltage therein, and when the person steps off the at least one tile (14), the bending stress is removed, thereby generating a current in the at least one elongated piezoelectric strip (24); wherein the at least one elongated piezoelectric strip (24) comprises a plurality of piezoelectric strips (24) electrically connected to one another in parallel.

2. The electrical power generating carpet (10) as recited in the previous claim, wherein the lower plate (20) of said at least one tile (14) is rigid.

3. The electrical power generating carpet (10) as recited in any of the previous claims, wherein the plurality of piezoelectric strips (24) are mounted on the top surface (23) of said lower plate (20) substantially parallel to one another.

4. The electrical power generating carpet (10) as recited in any of the previous claims, wherein a maximum dimension of the engaging member (36) is oriented substantially orthogonally to a maximum dimension of each elongated piezoelectric strip (24).

5. The electrical power generating carpet (10) as recited in any of the previous claims, further comprising at least one full-wave rectifier (40) electrically connected to the at least one elongated piezoelectric strip (24) for converting the induced current into direct current.

6. An electrical power generating carpet (10), comprising: a carpet (10); a plurality of tiles (14) embedded in the carpet (10), each of the tiles (14) having a pressure plate; a piezoelectric assembly disposed in each of the tiles (14) beneath the pressure plate, the piezoelectric assembly being configured for generating voltage and current in response to changes in pressure applied to the pressure plate; and an energy harvesting circuit electrically connected to the piezoelectric assembly, the energy harvesting circuit including a full wave rectifier circuit (40) and a buck converter circuit (BC) for regulating output of the full wave rectifier circuit (40); wherein said piezoelectric assembly comprises a plurality of piezoelectric sensor strips (24), each strip (24) having a respective set of leads; each said tile (14) comprising a flexible, resilient upper plate (30) and a rigid lower plate (20), the upper plate (30) being attached to the lower plate (20), said piezoelectric assembly being disposed between the upper plate (30) and the lower plate (20), the upper plate (30) being the pressure plate; and an elongated engaging strip (36) attached to a bottom surface of the upper plate (30) and bearing across the plurality of piezoelectric sensor strips (24) between opposing ends of the strip (24) so that when a person steps on the at least one tile (14), the upper plate (30) flexes and the elongated engaging strip (36) exerts a bending stress on the plurality of piezoelectric sensor strips (24), inducing a voltage therein, and when the person steps off the at least one tile (14), the bending stress is removed, thereby generating a current in the plurality of piezoelectric sensor strips (24).

7. The electrical power generating carpet (10) according to claim 6, wherein the piezoelectric sensor strips (24) are disposed parallel to each other and electrically connected in parallel.

8. The electrical power generating carpet (10) according to claim 7, wherein the elongated engaging strip (36) is oriented orthogonal to the piezoelectric sensor strips (24).

9. The electrical power generating carpet (10) according to claim 6, wherein said upper plate (30) and said lower plate (20) are each made from plastic.

10. The electrical power generating carpet (10) according to any of claims 6 to 9, wherein said carpet (10) comprises a moquette cover.