SPRING DISC ENERGY HARVESTER APPARATUS AND METHOD
First Claim
1. An energy harvesting apparatus, comprising:
- a first disc spring having an axial center and a radially outer peripheral area;
a second disc spring having an axial center and an a radially outer peripheral area;
said disc springs each having a first stiffness when no preload force is being applied thereto, and a second stiffness when a predetermined preload is applied thereto, with the second stiffness being less than the first stiffness, to thus enhance an ability of said disc springs to flex in response to vibration energy experienced by said apparatus;
an electrically responsive material secured to a surface of said first disc spring and spaced apart from said radially outer peripheral area, said electrically responsive material operating to generate an electrical output signal in response to changing levels of strain experienced by said electrically responsive material, in response to flexing motion of said first disc spring;
a support member for supporting said radially outer peripheral areas of said first and second disc springs; and
an adjustable fastening assembly operatively coupled to said first and second disc springs that applies a preload force to said disc springs to soften said disc springs such that said disc springs assume said second stiffness, said support member adapted to be secured to a vibrating structure such that vibration energy from said structure is transmitted to said disc springs, causing flexing of said disc springs.
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Accused Products
Abstract
An energy harvesting apparatus and method that is especially well suited for harvesting low frequency broadband vibration energy from a vibrating structure is presented. The apparatus includes a pair of disc springs that are arranged in an opposing relationship. A threaded fastening member and a threaded nut extend through apertures in each of the disc springs and enable a predetermined preload force to be applied to the disc springs. The preload effectively “softens” the disc springs, thus heightening the sensitivity of the disc springs to low frequency, low amplitude vibration energy. A piezoelectric material ring is secured to each of the disc springs. Each piezoelectric material ring experiences changes in strain as its associated disc spring deflects in response to vibration energy experienced from a vibrating structure. The electrical output from each piezoelectric material ring can be used to power or activate various forms of electronic sensors and devices, or it can be conditioned and stored in a circuit for later use.
70 Citations
20 Claims
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1. An energy harvesting apparatus, comprising:
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a first disc spring having an axial center and a radially outer peripheral area; a second disc spring having an axial center and an a radially outer peripheral area; said disc springs each having a first stiffness when no preload force is being applied thereto, and a second stiffness when a predetermined preload is applied thereto, with the second stiffness being less than the first stiffness, to thus enhance an ability of said disc springs to flex in response to vibration energy experienced by said apparatus; an electrically responsive material secured to a surface of said first disc spring and spaced apart from said radially outer peripheral area, said electrically responsive material operating to generate an electrical output signal in response to changing levels of strain experienced by said electrically responsive material, in response to flexing motion of said first disc spring; a support member for supporting said radially outer peripheral areas of said first and second disc springs; and an adjustable fastening assembly operatively coupled to said first and second disc springs that applies a preload force to said disc springs to soften said disc springs such that said disc springs assume said second stiffness, said support member adapted to be secured to a vibrating structure such that vibration energy from said structure is transmitted to said disc springs, causing flexing of said disc springs. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. (canceled)
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9. An energy harvesting apparatus, comprising:
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a pair of disc springs each having an inner surface and an outer surface, an axial center and a radial, outer peripheral area; an electrically responsive material secured to an outer surface of one of the disc springs, said electrically responsive material operating to generate an electrical output signal in response to changing levels of strain experienced by said electrically responsive material, in response to flexing motion of said disc springs; a support member for supporting said radial, outer peripheral areas of said disc springs such that said inner surfaces are in facing relationship, said support member further being supported, relative to a structure, to receive vibration energy experienced by said structure, so that said vibration energy causes flexing of said disc springs; and a fastening assembly including a threaded member and a threaded nut for securing said disc springs to said support member with an adjustable, predetermined preload force directed along said axial center of said disc springs sufficient to soften said disc springs from a first stiffness to a second stiffness, where said second stiffness is less than said first stiffness, to promote flexing thereof in response to said vibration. - View Dependent Claims (10, 11, 12, 14)
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13. (canceled)
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15. A method for forming an energy harvesting device, comprising:
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a) providing a disc spring; b) supporting an outer peripheral edge of said disc spring; c) applying a pre-load force to an inner peripheral edge of said disc spring directed along an axial center of said disc spring; d) while said pre-load force is being applied, using an adhesive compound to adhere a piezoelectric material to said disc spring; and e) waiting a predetermined time until said adhesive compound has cured; f) securing said disc spring to a support element using a fastening assembly; and g) using said fastening assembly and said support element to apply a predetermined preload force to said disc spring that causes a degree of deflection of said disc spring, said deflection being sufficient to place said disc spring in a condition of reduced stiffness. - View Dependent Claims (17, 18)
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16. The method of clam 15, wherein using said fastening assembly comprises using a threaded bolt having a threaded nut.
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19. A method for harvesting vibration energy from a vibrating source, comprising:
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securing a pair of disc springs to the vibrating source, where the disc springs are held in opposing relationship and pre-loaded with a force sufficient to substantially soften the disc springs and to make the disc springs sensitive to low frequency, low amplitude vibration energy; securing a material to a first one of the disc springs, where the material generates an electrical output signal in response to changes in strain that is experienced as said first disc spring flexes in response to vibration transmitted from said vibrating structure; and receiving electrical output signals from said material as said one disc spring flexes during vibration of said structure. - View Dependent Claims (20)
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Specification