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  Compressor and compression using motion amplificationUSPTO Application #: 20070267940Title: Compressor and compression using motion amplification Abstract: A compressor system (20, 20′, 20″) comprises a motion amplifier (22) which acts through a compressor head or piston (46) to compress fluid in a variable compression chamber (52). The motion amplifier (22) comprises a piezoelectric diaphragm (30) and drive electronics (26) for applying a drive signal to the piezoelectric diaphragm. The drive signal is generated to maintain the motion amplifier resonant at a predetermined frequency. The motion amplifier preferably comprises (in addition to the piezoelectric diaphragm) a reaction mass (34) connected to the piezoelectric diaphragm; a reacted mass (40) connected to the piezoelectric diaphragm; and, a reacted mass spring (50, 270) for resiliently carrying the reacted mass. The structure of the motion amplifier carried by the reacted mass spring (e.g., the piezoelectric diaphragm, the reaction mass, and the reacted mass) has a resonant frequency f2. The resonant frequency f2 is related to a spring constant K2 of the reacted mass spring and a sum of masses of the reaction mass and the reacted mass. Preferably the predetermined frequency is f2, which means that the drive signal is generated to maintain the motion amplifier resonant at a frequency f2, e.g., the drive signal is generated to urge the motion amplifier to the frequency f2 as its operational frequency. Driving the motion amplifier (22) at the frequency f2 achieves peak amplitude displacement of the motion amplifier, and thus peak displacement of the compressor head acting in the compression chamber. (end of abstract)
Agent: Nixon & Vanderhye, PC - Arlington, VA, US Inventor: David D. Wright USPTO Applicaton #: 20070267940 - Class: 310311000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070267940. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims the benefit and priority of the following U.S. provisional patent applications, all of which are incorporated herein by reference in their entirety: U.S. Provisional Patent application 60/747,286, entitled "COMPRESSOR AND COMPRESSION USING MOTION AMPLIFICATION"; U.S. Provisional Patent application 60/747,287, entitled "MOTION AMPLIFICATION USING PIEZOELECTRIC ELEMENT"; and U.S. Provisional Patent application 60/747,289, entitled "VIBRATION AMPLIFICATION SYSTEM FOR PIEZOELECTRIC ACTUATORS AND DEVICES USING THE SAME". This application is related to the following simultaneously-filed U.S. patent applications, both of which are incorporated herein by reference: U.S. patent application Ser. No. 11/______, (attorney docket 4209-160), entitled "MOTION AMPLIFICATION USING PIEZOELECTRIC ELEMENT" and U.S. patent application Ser. No. 11/______, (attorney docket 4209-162), entitled "VIBRATION AMPLIFICATION SYSTEM FOR PIEZOELECTRIC ACTUATORS AND DEVICES USING THE SAME". BACKGROUND [0002] 1. Field of the Invention [0003] The present invention pertains to amplification of motion such as vibration motion, and particularly to amplification of motion caused by a piezoelectric diaphragm or the like. [0004] 2. Related Art and Other Considerations [0005] Piezoelectric diaphragms have been employed in various types of pumps and actuators. As is well known, a piezoelectric material is polarized and will produce an electric field when the material changes dimensions as a result of an imposed mechanical force. This phenomenon is known as the piezoelectric effect. Conversely, an applied electric field can cause a piezoelectric material to change dimensions. [0006] One exemplary piezoelectric diaphragm, known as a ruggedized laminated piezoelectric or RLP.TM., has a central piezoelectric wafer which is laminated to a stainless steel substrate and preferably also has an aluminum cover laminated thereover. Examples of such RLP.TM. elements, and in some instances pumps employing the same, are illustrated and described in one or more of the following: PCT Patent Application PCT/US01/28947, filed 14 Sep. 2001; U.S. patent application Ser. No. 10/380,547, filed Mar. 17, 2003, entitled "Piezoelectric Actuator and Pump Using Same"; U.S. patent application Ser. No. 10/380,589, filed Mar. 17, 2003, entitled "Piezoelectric Actuator and Pump Using Same", and U.S. patent application Ser. No. 11/279,647 filed Apr. 13, 2006, entitled "PIEZOELECTRIC DIAPHRAGM ASSEMBLY WITH CONDUCTORS ON FLEXIBLE FILM", all of which are incorporated herein by reference. [0007] The displacement of a ruggedized laminated piezoelectric, while large compared to other piezoelectric devices, is still small in relation to the diameter of a pumping chamber in which it can be employed. Hence, compression ratios are still small, e.g., in a range on the order of 1.1 to 1.0, for example. An increased stroke for the piezoelectric diaphragm would facilitate an increased compression ratio. [0008] What is needed, therefore, and an object of the present invention, are apparatus, method, and technique for achieving motion amplification of a piezoelectric element. BRIEF SUMMARY [0009] A compressor system comprises a motion amplifier which acts through a compressor head or piston to compress fluid in a variable compression chamber. The motion amplifier comprises a piezoelectric diaphragm and drive electronics for applying a drive signal to the piezoelectric diaphragm. The drive signal is generated to maintain the motion amplifier resonant at a predetermined frequency. [0010] The motion amplifier preferably comprises a piezoelectric diaphragm and drive electronics for applying a drive signal to the piezoelectric diaphragm; a reaction mass connected to the piezoelectric diaphragm; a reacted mass connected to the piezoelectric diaphragm; and, a reacted mass spring for resiliently carrying the reacted mass. The reacted mass either forms or is connected to an actuator portion or actuator surface which, in turn, either forms or is connected to an actuator element. For example, the actuator portion or surface can serve as a piston head or a cylinder head, or as a surface or portion to which a further element such as an actuator shaft of the like can be connected. [0011] The structure of the motion amplifier carried by the reacted mass spring (e.g., the piezoelectric diaphragm, the reaction mass, and the reacted mass) has a resonant frequency f2. The resonant frequency f2 is related to a spring constant K2 of the reacted mass spring and a spring constant of any load upon which the reacted mass acts, as well as a sum of masses of the reaction mass and the reacted mass. Preferably the predetermined frequency is f2, which means that the drive signal is generated to maintain the motion amplifier resonant at a frequency f2, e.g., the drive signal is generated to urge the motion amplifier to the frequency f2 as its operational frequency. Driving the motion amplifier 22 at the frequency f2 achieves peak amplitude displacement of the motion amplifier, and thus peak displacement of the compressor head acting in the compression chamber. [0012] The drive electronics generates a drive signal to maintain the motion amplifier resonant at a predetermined frequency. In particular, in an example illustrated embodiment the drive electronics generates the drive signal to maintain a predetermined phase angle between the drive signal and a signal indicative of displacement of the motion amplifier system. To this end, the drive electronics comprises a sensor for sensing displacement of the motion amplifier and for generating the signal indicative of displacement of the motion amplifier. [0013] In one example embodiment, the piezoelectric diaphragm is mounted to and carried by the reacted mass. The reacted mass comprises a reacted mass cup which defines a reacted mass cavity. In one example implementation of this embodiment, a periphery of the piezoelectric element is held by the reacted mass cup while the center of the piezoelectric diaphragm is free to vibrate. The reaction mass is preferably centrally suspended from the piezoelectric diaphragm in the reacted mass cavity. [0014] Compressor assemblies of differing embodiments can incorporate the embodiments of motion amplifiers. The compressor assembly can include an amplifier base which carries the piezoelectric diaphragm, the reaction mass, the reacted mass, and the reacted mass spring. The amplifier base at least partially defines the compression chamber. The reacted mass spring can also at least partially defines the compression chamber. As one aspect of the technology, means are provided for resiliently mounting the amplifier base relative to the outside world, and thereby mitigating any damping caused by the outside world. [0015] In one example embodiment of a motion amplifier, the reacted mass spring comprises a diaphragm which also at least partially defines and covers the compression chamber. The diaphragm comprising the reacted mass spring is a preferably a corrugated diaphragm. Corrugation of the diaphragm provides increased motion for the motion amplifier. In an embodiment of a compressor assembly incorporating a diaphragm-type reacted mass spring, the amplifier base can have an inlet and an outlet for respectively intaking and exhausting fluid in accordance with displacement of the reacted mass (the reacted mass serving as the compression or piston head in the compression chamber). [0016] Another example embodiment of a motion amplifier comprises a bellows assembly. The bellows assembly has a sidewall for at least partially defining the compression chamber. The sidewall comprises and serves as the reacted mass spring. The bellows assembly further comprises an amplifier base for defining a valve assembly cavity. The valve assembly cavity and the compression chamber are sized to accommodate a valve assembly through which fluid is introduced into the compression chamber and compressed in the compression chamber by displacement of the motion amplifier. [0017] The technology also includes a method of operating a compressor assembly for compressing a fluid. The method includes displacing a motion amplifier having a compressor head in a compressor chamber, the motion amplifier comprising a piezoelectric diaphragm, a reaction mass connected to the piezoelectric diaphragm, a reacted mass connected to the piezoelectric diaphragm, and a reacted mass spring for resiliently carrying the reacted mass. The method further includes selectively admitting and exhausting fluid from the compressor chamber in accordance with displacement of the motion amplifier. The step of displacing the motion amplifier comprises generating and applying a drive signal to the piezoelectric diaphragm, the drive signal being generated to maintain the motion amplifier resonant at a predetermined frequency. Preferably, the method includes generating the drive signal to urge the motion amplifier to the frequency f2 as its operational frequency. [0018] A further aspect of the method includes resiliently mounting the compressor assembly (e.g., an amplifier base) relative to the outside world. [0019] The compressor assembly includes an inlet valve and an outlet valve for respectively admitting and exhausting fluid relative to the compression chamber. As another aspect of the technology, the natural frequency of the inlet valve and the natural frequency of the outlet valve are each greater than an operating frequency of the motion amplifier. For example, in an example embodiment, the natural frequency of each of the inlet valve and the outlet valve is at least twice the operating frequency of the motion amplifier. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. [0021] FIG. 1 is a front perspective view of an example embodiment of a compressor assembly which includes an example embodiment of a motion amplifier. Continue reading... Full patent description for Compressor and compression using motion amplification Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Compressor and compression using motion amplification patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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