COMPRESSOR AND COMPRESSION USING MOTION AMPLIFICATION
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 f 2. The resonant frequency f 2 is related to a spring constant K 2 of the reacted mass spring and a sum of masses of the reaction mass and the reacted mass. Preferably the predetermined frequency is f 2, which means that the drive signal is generated to maintain the motion amplifier resonant at a frequency f 2, e.g., the drive signal is generated to urge the motion amplifier to the frequency f 2 as its operational frequency. Driving the motion amplifier ( 22 ) at the frequency f 2 achieves peak amplitude displacement of the motion amplifier, and thus peak displacement of the compressor head acting in the compression chamber.
1 . A fluid compressor assembly comprising:
a motion amplifier comprising:
a piezoelectric diaphragm;
a reaction mass connected to the piezoelectric diaphragm;
a reacted mass connected to the piezoelectric diaphragm, the reacted mass forming a compression head;
a reacted mass spring for resiliently carrying the reacted mass;
an amplifier base for at least partially defining a compression chamber into which fluid is selectively admitted and exhausted;
drive electronics for driving the piezoelectric diaphragm and thereby displacing the compression head for compressing fluid in the compression chamber;
an inlet valve and an outlet valve for respectively admitting and exhausting fluid relative to the compression chamber.
2 . The apparatus of claim 1 , wherein the drive electronics generates and applies the drive signal to the piezoelectric diaphragm so as to maintain the motion amplifier resonant at a predetermined frequency.
3 . The apparatus of claim 2 , wherein structure of the motion amplifier carried by the reacted mass spring has a resonant frequency f 2 , wherein the predetermined frequency is f 2 , and wherein the drive signal is generated to urge the motion amplifier to the frequency f 2 as its operational frequency.
4 . The apparatus of 3 , wherein the resonant frequency f 2 is related to a spring constant K 2 of the reacted mass spring and a sum of masses of the reaction mass and the reacted mass.
5 . The apparatus of 1 , wherein 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.
6 . The apparatus of claim 5 , wherein 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.
7 . The apparatus of 1 , wherein a periphery of the piezoelectric diaphragm is held and carried by the reacted mass.
8 . The apparatus of 1 , wherein the piezoelectric diaphragm is mounted to and carried by the reacted mass; wherein the reacted mass comprises a reacted mass cup which defines a reacted mass cavity, and wherein the reaction mass is suspended from the piezoelectric diaphragm in the reacted mass cavity.
9 . The apparatus of claim 1 , further comprising an amplifier base for at least partially defining a compression chamber, wherein the reacted mass spring also at least partially defines the compression chamber, and further comprising means for resiliently mounting the amplifier base relative to the outside world.
10 . The apparatus of claim 9 , wherein the amplifier base carries the piezoelectric diaphragm, the reaction mass, the reacted mass, and the reacted mass spring.
11 . The apparatus of 1 , further comprising an amplifier base for at least partially defining a compression chamber, wherein the reacted mass spring comprises a diaphragm which also at least partially defines and covers the compression chamber, the amplifier base having an inlet and an outlet for respectively intaking and exhausting fluid in accordance with displacement of the reacted mass.
12 . The apparatus of claim 11 , wherein the diaphragm comprising the reacted mass spring is a corrugated diaphragm.
13 . The apparatus of claim 11 , further comprising means for resiliently mounting the amplifier base relative to the outside world.
14 . The apparatus of 1 , further comprising a bellows assembly, and wherein the bellows assembly comprises a sidewall for defining a compression chamber, the sidewall comprising the reacted mass spring.
15 . The apparatus of claim 14 , wherein the bellows assembly further comprises an amplifier base for defining a valve assembly cavity, the valve assembly cavity and the compression chamber being 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.
16 . The apparatus of claim 14 , wherein the bellows assembly further comprises an amplifier base, and further comprising means for resiliently mounting the amplifier base relative to the outside world.
17 . The apparatus of claim 1 , wherein the natural frequency of the inlet valve and the natural frequency of the outlet valve are greater than an operating frequency of the motion amplifier.
18 . The apparatus of claim 17 , wherein the natural frequency of each of the inlet valve and the outlet valve is at least twice the operating frequency of the motion amplifier.
19 . A method of operating a compressor assembly for compressing a fluid comprising:
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;
selectively admitting and exhausting fluid from the compressor chamber in accordance with displacement of the motion amplifier;
wherein the 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.
20 . The method of claim 19 , wherein structure of the motion amplifier carried by the reacted mass spring has a resonant frequency f 2 , wherein the predetermined frequency is f 2 , and further comprising generating the drive signal to urge the motion amplifier to the frequency f 2 as its operational frequency.
21 . The method of claim 20 , wherein the resonant frequency f 2 is related to a spring constant K 2 of the reacted mass spring and a sum of masses of the reaction mass and the reacted mass.
22 . The method of claim 19 , further comprising generating the drive signal to maintain a predetermined phase angle between the drive signal and a signal indicative of displacement of the motion amplifier.
23 . The method of claim 22 , further comprising sensing displacement of the motion amplifier and generating the signal indicative of displacement of the motion amplifier.
24 . The method of claim 19 , wherein the compressor assembly further comprises an amplifier base for at least partially defining the compression chamber, and further comprising resiliently mounting the amplifier base relative to the outside world.
25 . The method of claim 24 , mounting the piezoelectric diaphragm, the reaction mass, the reacted mass, and the reacted mass spring on the amplifier base.