A Dual Bimorph Assembly

Abstract

A dual bimorph assembly includes a multilaminar element structure where each elements includes a perforated metal layer, a suffusing conductive ink layer and a transductive assembly. A retainer assembly is provided with conductive tabs and a retainer through connector electrically connects metal layers.

Claims

1. A wire-free and adhesive free planar dual bimorph device comprising: a perforated outer top metal layer having a tip mass clamping hole disposed in a first end section and a second end section, and an off-center section including a retainer clamping hole and a terminal hole; a first suffusing conductive ink layer that interlocks with the perforation of the outer top metal layer a first transductive assembly including a transductive element having a tip mass spacer including a tip mass hole disposed at a first end and the having a tip mass spacer including a tip mass clamping hole disposed at a second end and an off-center section including a terminal hole and a retainer clamping hole, the transductive assembly being suffused to the first suffusing conductive ink layer; a second suffusing conductive ink layer that suffused to the first transductive assembly; a perforated central metal layer having a tip mass clamping hole disposed in a first end section and a second end section, and an off-center section including a terminal clamping hole and a retainer clamping hole, said the second suffusing conductive ink layer being interlocked with the perforations of the central metal layer; a third suffusing conductive ink layer that interlocks with the perforation of the central metal layer; a second transductive assembly including a transductive element having a tip mass spacer including a tip mass hole disposed at a first end and the having a tip mass spacer including a tip mass clamping hole disposed at a second end and an off-center section including a terminal hole and a retainer clamping hole, the transductive assembly being suffused to the third suffusing conductive ink layer; a fourth suffusing conductive ink layer that suffused to the second transductive assembly; and a perforated outer bottom metal layer having a tip mass clamping hole disposed in a first end section and a second end section, and an off-center section including a retainer clamping hole and a terminal hole, said the fourth suffusing conductive ink layer being interlocked with the perforations of the outer metal layer; a retaining assembly having through holes aligned with the clamping retainer holes and the terminal clamping holes of the off-center section and that accepts a first and a second independent conductive tabs; a retainer through connector that electrically connects the top outer metal layer and bottom outer metal layer and the first conductive tab located and a terminal through connector that electrically connects a second conductive tab and the central metal layer.

2. The assembly of claim 1 further comprising a first tip mass attached to the first tip mass clamping hole and a second tip mass attached to the second tip mass clamping hole.

3. The assembly of claim 1 wherein at least one of the first and second transductive assemblies is comprised of two separate transductive materials either side of the off-center section.

4. The assembly of claim 1 further comprising of multiple disposed cantilever beam assemblies of 1 that share common centroidal positive and negative thru-connectors.

Description

VI BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. The use of cross-hatching and shading within the drawings is not intended as limiting the type of materials that may be used to manufacture the invention.

[0019] FIG. 1A depicts a sectional side view of a laminate layer assembly according to an embodiment of the invention.

[0020] FIG. 1B shows a top view of the laminate layer assembly of FIG. 1A.

[0021] FIG. 2A depicts a sectional side view of a laminate layer assembly according to another embodiment of the invention.

[0022] FIG. 2B illustrates a top view of the laminate layer assembly of FIG. 2A.

[0023] FIG. 3A shows a sectional side view of a laminate layer assembly including a conductive metal layer according to an embodiment of the invention.

[0024] FIG. 3B illustrates the laminate layer of FIG. 3A after application of a thermal profile.

[0025] FIG. 3C depicts the laminate layer of FIG. 3B with access material removed.

[0026] FIG. 4A shows a perspective view of a laminate layer assembly with mechanical and electrical connectors in accordance with an embodiment of the invention.

[0027] FIG. 4B illustrates an exploded view of the laminate layer assembly of FIG. 4A.

[0028] FIG. 5 depicts a perspective view of a laminate layer assembly having mechanical and electrical connectors according to an embodiment of the invention.

[0029] FIG. 6 shows an exploded view of a N-fold high deformation high temperature capable wire-free bimorph cantilever multilayer device in accordance with an embodiment of the invention.

[0030] FIG. 7A 11 is a perspective view a wideband spectrum capable cantilever multilaminate device in accordance with the present invention.

[0031] FIG. 7B is an exploded view of the device of FIG. 7A.

[0032] FIG. 7C is a top view of the device of FIG. 7A.

[0033] FIG. 7D is a side view of the device of FIG. 7D.

VII DESCRIPTION OF THE EMBODIMENTS

[0034] The description of the invention is provided by the incorporated figures, none of which are to scale, but are instead intended to explicate the key features in the design and construction of the invention. In reference to FIGS. 1A and 1B, a multilaminar arrangement 400 is shown including a first transductive assembly layer 303a positioned between a perforated top metal plate 301a and a perforated center metal plate 305. Similarly, a second transductive assembly layer 303b is positioned between a perforated bottom metal plate 301b and a perforated center plate 305. A a thin conductive metal layer 423 disposed between transductive assembly layer 303b and perforated bottom metal plate 301b and a similar conductive metal layer 421 is disposed between transductive assembly layer 303b and perforated center plate 305. In keeping with the invention, to facilitate both for construction and function, in some embodiments, perforated top metal plate 301a and perforated bottom metal plate 301b are similarly planar sized. In some embodiments, transductive assembly layers 303a and 303b are also similarly planar sized, but are of equal or smaller planar size than the planar size of top and bottom perforated metal plates 301a and 301b. In some embodiments, transductive assembly layers 303a and 303b and top and bottom perforated metal plates 301a and 301b have the same planar width but not necessarily the same thickness. Perforated center metal plate 305 is of greater length along its main axis than either perforated top and bottom metal plates 301a and 301b and transductive layers 303a and 303b. Thus, when perforated top, center and bottom metal plates 301a, 305 and 301b and transductive assembly layers 303a and 303b are commonly aligned at one end (referred to herein as the common alignment end 417 of device 400), center metal plate 305 will protrude a certain length d beyond the similar conductive opposing ends of transductive assembly layers 303a and 303b and top and bottom metal plates 301a and 301b (referred to herein as the protrusion end 419 of device 400).

[0035] Referring to FIGS. 4A and 4B, in some embodiments, transductive assembly layers 303a and 303b include thin non-conductive spacers 418a, 418b, 502a, and 502b disposed at respective end portions of transductive members 303aa and 303bb and positioned between perforated center plate 305 and the ends of top and bottom perforated plates 301a and 301b. As shown in FIG. 4A, in some embodiments a first tip mass acceptor channel 528 is configured for optional tip mass insertion and is formed by aligned cut outs through perforated top metal plate 301a, spacer 502a, perforated center plate 305, spacer 502b, and perforated bottom metal plate 301b. FIG. 4B shows cut outs 528a formed in spacers 502a and 502b that are vertically aligned with tip mass cut outs formed at a first end portion of perforated top metal plate 301a, perforated center plate 305 and perforated bottom metal plate 301b to form tip mass acceptor channel 528.

[0036] Referring to FIGS. 8A and 8B, to facilitate electrical connection, a structural connector 501 is provided. In some embodiments, structural connector 501 may take the form of a block of stiff, non-conductive material incorporating several matching cut-outs 402 and 409. In keeping with the invention, block 501 may be mated with device 400 such that cut outs 402 and 409 are aligned through perforated top and bottom metal plates 301a, 301b, transductive assembly layers 303a, 303b, and block 501. In some embodiments where transductive assembly layers 303a and 303b include spacers 418a and 418b. In such embodiments, spacers 418a and 418b are provided with cut outs 402.

[0037] A positive polarity metal tab 416 is provided with cut out 402 and is mated with block 501 such that cut out 402 aligns with cut out 402 of block 501. Positive polarity tab 416 also incorporates a connection point 522 configured to accept an external positive polarity lead, or other, connector. A negative polarity metal tab 415 is provided with cut out 409 and is mated with block 501 such that cut out 409 aligns with cut 409 of block 501. Negative polarity tab 415 also incorporates a connection point 524 configured to accept an external negative polarity lead, or other, connector. In some embodiments block 501 may incorporate recessed regions in its base as to enable flush mounting of tabs 415 and 416.

[0038] In keeping with an aspect of the invention, a non-conductive spacer 520 may be disposed in a vertical gap between the protrusion of 305 and a top surface of block 501. Spacer 520 incorporates cut-outs 409 which are aligned with cut-outs 409 of perforated central plat 305, block 501, and negative polarity tab 415.

[0039] Referring again to FIG. 1, a thin conductive metal layer 422 is disposed between 301a and transductive assembly layer 303a excepting planar region corresponding to spacers 418a and 502a. Similarly, a thin conductive metal layer 420 is disposed between perforated center plate 305 and transductive assembly layer 303a excepting planar region corresponding to spacers 418a and 502a. A thin conductive metal layer 423 is disposed between perforated center plate 305 and transductive assembly layer 303b excepting planar region corresponding to spacers 418b and 502b. Similarly, a thin conductive metal layer 421 is disposed between perforated center plate 305 and transductive assembly layer 303b excepting planar region corresponding to spacers 418a and 502a.

[0040] Referring to FIGS. 2A and 2B, with the laminates carefully aligned to form a common planar piece with common end 417, one or more common positive polarity electrical connectors 505, such as a thru-bolt or screw arrangement, may be installed through each vertically aligned cut-out 402 to electrically connect perforated top metal plate 301a, perforated bottom metal plate 301b, and positive polarity electrical tab 416. In keeping with an aspect of the invention, connectors 505 are not electrically connected to perforated center plate 305. Importantly, connector 505 plays a dual role of both electrically connecting the outward facing side of both transductive layer 303a and transductive layer 303b to positive electrical tab 416 while simultaneously mechanically affixing all the layers of device 400, block 501, and tab 416.

[0041] Still referring to FIGS. 2A and 2B, with the laminates still carefully aligned to form a common planar piece with common end 417, one or more common negative polarity electrical connectors 406, such as a thru-bolt or screw arrangement, may be installed through each vertically aligned cut-out 409 to electrically connect perforated center plate 305 and negative electrical tab 415. Note that connectors 406 do not electrically connect to perforated top metal plate 301a or perforated bottom metal plate 301b. Importantly, connectors 406 play a dual role of both electrically connecting the perforated center plate 305 to the external electrical tab 415 while simultaneously mechanically affixing central metal layer 305, spacer 418, block 501, and metal tab 415.

[0042] Again, referring to FIGS. 2A and 2B, with the laminates still carefully aligned to form a common planar piece with common end 417, common connectors 428, such as a thru-bolt or screw arrangement, may be installed through tip mass acceptor hole 528. This arrangement mechanically affixes all layers of device 400 at their common end.

[0043] Referring to FIGS. 1A and 1B, a locking mechanism 408b may be attached to each thru-connector 406b at the underside of tab 415. A locking mechanism 506 may be attached to thru-connector 505 at the underside of tab 416. Referring to FIGS. 2A and 2B, a locking mechanism 426 may be attached to tip thru-connector 428 at the underside of 301b. Suitable locking mechanisms include standard threaded nuts and other similar known devices. By tightening all locking mechanisms in a uniform manner acts to induce an orthonormal compressive force across the laminate structure 400 which is may be adjusted through selective torqueing or tightening connectors 408b, 506, and 426.

[0044] Prior to subjecting the pre-constrained article 400 to a thermal profile, a static mass can optionally, as needed, be positioned on top of the laminate 400 as to apply a normal loading force on 400. Adding such a mass will further increase the constraining static pressure applied during the thermal cycle process.

[0045] Referring to FIGS. 3A-3C, subsequent to introducing desired static laminate pressure on the layers of device 400, either through the locking process of the thru-connectors or possibly adding additional static mass, in keeping with the invention, device 400 is subjected to a thermal profile 308 that causes suffusion metal layers 422, 420, 421 and 423 to cross-link with respective adjacent members namely, top metal plate 301a, bottom metal plate 301b, and center metal plate 305 and the transductive assembly layers 303a and 303b and to suffuse from state 307 and 314 to 310 and 311 into the perforations of top metal plate 301a, bottom metal plate 301b, and center metal plate 305. Suitable materials for suffusion metal layers 422, 420, 421 and 423 include Ag, Cu, Ni, Pt and Pd inks.

[0046] In accordance with an aspect of the invention, thermal profile 308 has a rise region, steady state region and a fall region. Thermal profile 308 may be determined by the selection of materials multilaminar device 400, the pre-loading of multilaminar device 400, and the overall dimensions of the layers that comprise multilaminar device 400. This thermal process acts to form an extremely strong mating between all the interlaminate layers of 400. In some embodiments, thermal profile 308 includes rise region whereby temperature increases at a rate of 3 C./min from room temperature to 500 C., holds for 30 minutes at 500 C., and decreases at a rate of 3 C./min to room temperature. Subsequent to applying the thermal profile 308, any excess conductive metallic suffusion material 310 should be removed as to present a flat surface 313 at the top and bottom metal plates 301a, and 301b. The exact same process applying to the mating of 305, 303b, and 301b.

[0047] For striction transductive materials such as piezoelectric and electrostrictive materials this bonding process can be further strengthened by pre-electroding the top and bottom surfaces of such transductive materials 306a and 306b with a thin conductive metallic layer prior to their installation into the laminate construction 400. Subsequent to application of thermal profile 308, bolt or screw arrangement 428 installed through the tip mass acceptor hole 528 may be removed to form an uninterrupted common laminate end 417 of multilaminar structure 400. Further, multilaminar device 400 may then be polarized, either magnetically or electrically, as to activate the transductive properties of transductive assembly layers 303a and 303b.

[0048] Referring to FIG. 5, in order to better operate over a target frequency band, a tip mass 428 may be incorporated into the tip acceptor hole 402. Adding a mass serves to lower the frequency band of operation of the multilaminar device 400 either as a sensor, energy harvester or as an actuator. Tip mass 428 is again attached by attaching mechanism 426 at the underside of metal layer 301b.

[0049] In some applications, especially those related to use of multilaminar device 400 as an energy harvesting mechanism, it may be advantageous to increase the stiffness of the joint between multilaminar device 400 and its applied substructure, here represented by block 501. Referring to FIG. 5, such a stiffening may be realized by introducing stiffening plates or shims 504 positioned above multilaminar device 400 and that lock multilaminar device 400 and block 501 by though connectors 411a and 411b that are transversally disposed in shim stiffener through connector cut-outs 410a and 410b, respectively. In some embodiments, each through connector may be provided with a corresponding locking mechanism at the underside of block 501.

[0050] As described hereinabove and depicted in FIGS. 1A and 1B, multilaminar device 400 comprises three perforated, stacked metal layers 301a, 305, and 301b that mechanically capture and electrically mate with transductive assembly layers 303a and 303b as described. In keeping with the invention, a multilaminar assembly may be formed by combining a plurality of multilaminar devices 400. FIG. 10 depicts such a device. The level 1 device 400 is depicted. The number of metal and transductive layers can be extended to a further set of 400 levels 400(level 1) to 400(level N) by adding additional thin metal coating such as silver 423(1) to top surface of perforated top metal plate 301a, then a first transductive assembly layer, and then a further silver layer on the top surface 421(1) of this added transductive assembly layer, a second center metal plate 305 atop this added silver layer 420(1), and then a further silver layer 422(1) on top of second center metal plate 305, then a second transductive layer atop silver layer 422(1), then a further silver layer on the top surface of the second transductive layer, then a second perforated top metal plate 301a; these added layers forming 450_(1) the first reduced copy of 400. Repeating this addition for 450_(1) to 450_(N1) yields an N-level multilaminar assembly 470.

[0051] A wider band capable embodiment of multilaminar device 400 can be obtained by moving the positive and negative cut-outs and thru-connectors from the protrusion end of 400 to a selected position that is some length along the multilaminate construction of 400. Referring to device 680 of FIG. 7A-7D, the top and bottom perforated metal plates 701a and 701b incorporate identically placed tabs positioned at length h of multilaminar device 400 of length l, therefore dividing multilaminar device 400 into two sections, one having a length h and the other having a length l-h. In accordance with an aspect of the invention, hl/2. The ratio of h to (l-h) is important to defining the wider frequency response. As illustrated in FIG. 7B, the transductive layers now comprise of two sections; the first transductive assembly layer includes transductive sections 303c and 303d that are positioned between top spacers 702a and 702b and a non-conductive spacer 703a respectively. Similarly, a second transductive layer consists of sections 303e and 303f that are positioned between bottom spacers 702c and 702d and a non-conductive spacer 703b, respectively.

[0052] Referring to FIG. 7C, each such top and bottom perforated metal plate 701a and 701b incorporates tip access cut-outs at first and second ends configured to receive a tip mass 431a and 431b. First and second central plate tabs incorporate positive polarity cut-out holes 402a and 402b through which are inserted positive polarity thru-connectors 505a and 505b that mechanically affix perforated top metal plate 701a, non-conductive spacer 703a, perforated center plate 705, non-conductive spacer 703b, perforated bottom metal plate 701b, positive polarity tab 416 and locking arrangement 505 positioned underneath positive polarity tab 416. In some embodiments only one of through connectors 505a and 505b are mechanically engage with tab 416. In other embodiments both through connectors 505a and 505b engage with tab 416. Similarly, perforated center plate 705 incorporate a cut-out 409 as to enable negative polarity thru-connector 406 to be countersunk through cut-outs 409 in perforated top and bottom metal plates 701a and 701b as to mechanically and electrically affix perforated center plate 705 to negative polarity metal tab 415.

[0053] It will be obvious to those familiar with the bimorph devices that the dual bimorph embodiment so described can be readily be adapted to further embodiments having three (triangular positive and negative polarity connector arrangement at h) or more (circular positive and negative polarity connector arrangement at h) disposed sections. Each such section possibly including different transductive materials and differing tip masses.

[0054] Further, the embodiment depicted in FIGS. 7A-7D is a metal/ceramic structure that employs a central electrical mechanical arrangement positioned along its length yielding a 2-spoke design comprising of two unequal, and independent, cantilever beams exhibiting distinct frequency responses. The addition of unequal tip masses further separates these independent frequency bands from each other. The result is that this embodiment of the invention displays superior performance as a sensor or energy harvester over a single cantilever type device. The skilled artisan will recognize that the 2-spoke design may readily be transitioned to an N-spoke design for N>2 wherein the central electrical mechanical arrangement is in a geometry such as a circular design that is conducive to splaying N multiple unequal beam lengths with N unequal tip masses as to achieve an even wider effective coupling with mechanical or magnetic energy across the spectrum.

[0055] In keeping with the invention, transductive elements of the invention may be comprised of piezoceramic or electrostrictive materials and as such will provide for extremely radhard embodiments. For example, thin film and thick film piezoceramic materials have been tested under SEE, SEU, and X-ray. Although piezoelectric thin films can be susceptible to radiation-induced degradation over long durations, thick film ceramics of interest in this invention are far less susceptible from such effects. Indeed, it has been determined that thick film piezoceramics can operate over extended periods into years under continuous gamma radiation exposure. As a consequence, because the invention completely eliminates all wiring and adhesives, employing transductive elements in the invention as high temperature capable thick-film piezoceramics along with high temperature capable metal layers and thru-connectors provides embodiments of the invention that are both very radhard and can operate to very high temperatures. For example, by assembling the laminate of the present invention to consist of lithium niobate (LiNbO3), YCa.sub.4O(BO.sub.3).sub.3 (YCOB) or aluminum nitride (AlN) piezoelectric ceramic layers, results in devices of the present invention that can stably operate to 800 C. range. For perforated metal layers, suitable materials include Invar due to its remarkably low coefficient of thermal expansion (CTE). Nickel alloys may be suitable for applications for applications over 1000 C.

[0056] The laminar construction of the present invention is advantageous in that it enables a direct, low cost, route to simple laminar construction of sensors, actuators and energy harvesters that can reliably function to very high temperatures.

[0057] Depending upon the class of materials employed in the fabrication a single level or N-level constructed bimorph can effectively operate as a cantilever actuation mechanism, a sensor mechanism or an energy harvester mechanism each capable of high-power operation over high thermal ranges. As with conventional piezoelectric bimorphs, tip masses can be added as to adjust the resonant frequencies of said device. By arranging multiple bimorph mechanisms of the invention that are of differing lengths as to possess a common fixed termination point, the device can act as a broadband sensor or energy harvester that can provide high sensitivity or high-power generation in a very high temperature environment. In other embodiments, multilaminate structures according to the invention may have a disc geometry replacing the cantilever. Importantly, the resulting mechanisms of the invention eliminate the need for the usual electrode wiring that of itself can be of issue when operating at higher temperatures.

[0058] Although the present invention has been described in terms of particular preferred embodiments, it is not limited to those embodiments. Alternative embodiments, examples, and modifications which would still be encompassed by the invention may be made by those skilled in the art, particularly in light of the foregoing teachings. For example, a number of factors affect the performance of the present invention including geometry, number and type of metal layers, thickness ratio of active to inactive layers, tip mass(es), transductive material compositions, pre-stresses, and applied electrical lead characteristics. Further, the skilled artisan will recognize that the resulting wire free and adhesive free assembly can equally function as a sensor, actuator, or energy harvester depending upon how the electrical connections at the base of the mounting block are configured. With the positive polarity with respect to the negative polarity terminals configured as passive, the device acts as a sensor or energy harvester; when an AC potential is applied to the positive polarity terminals with respect to the negative polarity terminals the device acts in the function of an actuator.

VII INDUSTRIAL APPLICABILITY

[0059] The present invention may be employed in various systems and devices that require energy harvesters, actuators and/or sensors to operate in extreme conditions such as hypersonic vehicles, hypersonic weapons, re-entry vehicles, communication satellites, jet engines, industrial processes, space propulsion systems and other deep space devices. Further, the invention may be used in a variety of high temperature, high radiation sensor implementations including strain sensors, pressure sensors, gas sensors and accelerometers.