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Piezoelectric pumpRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Collapsible Wall Pump, Diaphragm Type, Piezoelectric DrivenPiezoelectric pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070140875, Piezoelectric pump. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE DISCLOSURE [0001] This disclosure pertains to the field of piezoelectric pumps, and, in particular, nonmagnetic piezoelectric pumps which may be implanted inside a living body without causing a later magnetic interaction problem for Magnetic Resonance Imaging (MRI) problem for MRI scans. BACKGROUND OF THE DISCLOSURE [0002] Piezoelectric materials and their various applications have been known in the art for a number of years and their use as a pumping mechanism for fluids are well established. The piezoelectric effect includes the application of a potential electrical difference across a piezo-material, such as a crystal, resulting in the material undergoing a change in size. In one example, each of the elements of a stack of piezoelectric elements deforms with two dimensional extension, accompanied by a thickness deformation that results in the mechanical motion used to move a piston type structure, the piston being used in a conventional manner to move a fluid to be pumped. [0003] The construction of such a piezoelectric pump may be formed by placing the stack of piezoelectric elements on the mechanical piston and electrically activating the elements to cause the piston to move in the desired manner. Other forms of piezoelectric pumps include various mechanical displacement means wherein the mechanical motion is provided by the electrically excited piezoelectric elements that are connected to various types of mechanical displacement devices. [0004] One form of a mechanical pump for fluids is known as a "finger" pump, and includes a series of finger-like elements that perform a rhythmic, wave-like motion along a flexible tube with the motion causing the fluid in the tube to be moved from one end of the tube to the other. This "finger" pump can be constructed using piezoelectric elements as the "fingers." The use of a varying electric field applied to the piezoelectric elements, causes a rhythmic motion used to transport the fluid in the tube. [0005] Over the years, there have been a number of developments in the area of piezoelectric pumps. [0006] U.S. Pat. No. 5,192,197, issued to Culp, discloses a piezoelectric pump in which a plurality of piezoelectric elements, noted as waveplates, are resonated electrically by a multiplicity of electrical phases and used to create traveling waves. The waveplates are arranged to touch at the wave crests with the fluid in the volumes between the wave crests carried along with the rhythmic motion of the waves. It is noted that this pump can be used to move fluids in either direction by changing the electric phases to change the direction of the rhythmic motion of the fingers. [0007] U.S. Pat. No. 6,004,115, issued to da Costa, discloses a compressor for refrigeration system wherein a plurality of pistons comprised of piezoelectric material arranged within a hermetic shell are caused to compress in adjacent pairs such that fluid contained in the spaces between the tops of the pistons and the shell moves from one adjacent piston pair to the next until the fluid is moved from the entrance of the shell to the exit portion of the shell. Each of the pistons contract relative to the shell when in a second energizing condition so as to provide the space between the tops of the piston and the shell. When in the first energizing condition, the piston tops occupy the space to the top of the shell, forcing the fluid to move to an open space. An electrical energizing system is used to impart electrical signals to the piezoelectric pistons in a selective fashion to establish the pattern of first and second energizing conditions, and so cause the displacement of the fluid from the entrance to the exit of the compressor. [0008] U.S. Pat. No. 4,808,084, issued to Tsubouchi et al, discloses an apparatus for transferring small amount of fluid and which includes at least three vibration pumps arranged serially, with a fluid transfer pipe between each of the vibration pumps. The pumps themselves are comprised of piezoelectric elements that are caused to vibrate via an electrical signal control system, the signals applied to each of the adjacent pumps operated at a predetermined phase difference. [0009] U.S. Pat. No. 3,418,980, issued to Benson, discloses a fuel injector-ignition system wherein a stack of piezoelectric elements are energized in such a fashion so as to cause the stack to deform axially and move a plunger attached thereto, the axial movement of the plunger used to draw fuel into an annular chamber. [0010] U.S. Pat. No. 5,338,164, issued to Sutton, et al. discloses a positive displacement pump wherein a plurality of chambers in a stack have diaphragms therein, the diaphragms having an electro-deformable material associated with each of the diaphragms. The arrangement of the pump features stacks of chambers having a common diaphragm between adjacent chambers such that when a diaphragm is deformed to increase the volume of one chamber, the adjacent chamber is simultaneously decreased in volume. Thus, a pumping action is achieved in the pump. [0011] As noted above, the use of piezoelectric elements for use in various ways to move fluid from one location to another is known. However, a piezoelectric material having voids contained within the body of the material moving fluid by changing shape or size (e.g. similar to a sponge) has not been proposed. SUMMARY OF THE DISCLOSURE [0012] In the present disclosure, a piezoelectric material can be made porous to absorb fluids. When the absorbent piezoelectric material is electrically stimulated, the piezoelectric material changes shape and either draws in or expels any nearby fluid in a fashion similar to a sponge. A linear arrangement of such absorbing piezoelectric devices would allow fluid to be passed along from one element to the next in a bucket brigade fashion. [0013] In another embodiment of the disclosure, a secondary fluid can be made to flow into and out of the piezoelectric elements by the aforementioned action. Specifically, the secondary fluid acts upon the wall of structure that contains the primary fluid, creating a pulsating action vis a vis a primary fluid which in turn moves the fluid through the pump. [0014] In yet another embodiment of the disclosure, the piezoelectric elements can be made to act upon a mechanical piston either directly or via the secondary fluid which moves the primary fluid. In another embodiment the fluid of the piezoelectric pump may act upon a fluid filled membrane to move the fluids therein. [0015] In one embodiment of the disclosure, a piezoelectric pump allowing for fluid flow has been developed for use in micro-fluid delivery systems. A sequential arrangement of piezoelectric elements is disclosed, with each element of the sequential arrangement being expandable due to electric excitation applied to their individual electrodes. Removal of the electrical voltage from the piezoelectric elements results in the return of the elements to their original size and shape. Concomitantly (or subsequently) a change in the size of the contained voids occurs, resulting in the release of the fluid contained within those voids. Fluid can thus be made to flow sequentially, from one piezoelectric element to the adjacent element. The construction of the piezoelectric elements is comprised of a material that is of a slightly elastic, or sponge-like form that expands when electrical voltage is applied thereto, and which contracts when the voltage is removed. Voids formed during construction of the pump can be used as a fluid transport pathway or channel either directly, or by the use of a secondary fluid that is caused to act upon tube or mechanical piston to move a primary fluid. [0016] In an alternative embodiment of the disclosure, each element of the sequential arrangement can contract due to electric excitation applied to their individual electrodes. Removal of the electrical voltage from the piezoelectric elements results in the return of the elements to their original size and shape. Concomitantly (or subsequently) an increase in the size of the contained voids occurs, resulting in the absorption of the fluid. Fluid can thus be made to flow sequentially, from one piezoelectric element to the adjacent element. The construction of the piezoelectric elements is comprised of a material that is of a flexible, or sponge-like form that contracts when electrical voltage is applied thereto, and which expands when the voltage is removed. Voids formed during construction of the pump can be used as a fluid transport pathway or channel either directly, or by the use of a secondary fluid that is caused to act upon tube or mechanical piston to move a primary fluid. BRIEF DESCRIPTION OF THE FIGURES [0017] FIG. 1 is a schematic view of a piezoelectric element; [0018] FIG. 2 is a schematic view of a series arrangement of piezoelectric elements used in a pump; [0019] FIG. 3 is a schematic view of an alternate embodiment of the arrangement of piezoelectric elements used in a pump; [0020] FIG. 4 is a schematic view of an embodiment of a piezoelectric element of the present disclosure; Continue reading about Piezoelectric pump... Full patent description for Piezoelectric pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Piezoelectric pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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