Closed-loop piezoelectric pump
First Claim
1. A piezoelectric pump comprising:
- a pump housing;
a movable diaphragm located within the pump housing and defining a pumping chamber within the pump housing, the pumping chamber having an inlet for admitting fluid into the pumping chamber and an outlet for emitting fluid;
a piezoelectric transducer coupled to the moveable diaphragm and operable to move the diaphragm and thereby change the volume of the pumping chamber, wherein the piezoelectric transducer is adapted to sense pressure fluctuations in the pumping chamber;
a fluidic valve, operable to restrict fluid flow from the pumping chamber through the inlet; and
a flow restrictor, operable to restrict fluid into the pumping chamber through the outlet, wherein the flow restrictor has an acoustic impedance approximately equal to the acoustic impedance of the fluid, so that reflection of sound from the flow restrictor is small relative to transmission of sound through the flow restrictor.
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Accused Products
Abstract
A closed-loop piezoelectric pump is disclosed for use in a fluid delivery system. The pump housing includes a movable diaphragm that defines a pumping chamber within the pump housing, the pumping chamber having an inlet for admitting fluid and an outlet for emitting fluid. A piezoelectric transducer is coupled to the moveable diaphragm and operates to produce a pumping action by varying the volume of the pumping chamber. The piezoelectric transducer may be used to generate an acoustic pressure pulse within the fluid delivery system and to sense reflections of the acoustic pressure pulse caused by impedance changes downstream of the pump. Properties of the fluid path downstream of pump may be determined from the characteristics of the sensed reflections.
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Citations
25 Claims
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1. A piezoelectric pump comprising:
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a pump housing; a movable diaphragm located within the pump housing and defining a pumping chamber within the pump housing, the pumping chamber having an inlet for admitting fluid into the pumping chamber and an outlet for emitting fluid; a piezoelectric transducer coupled to the moveable diaphragm and operable to move the diaphragm and thereby change the volume of the pumping chamber, wherein the piezoelectric transducer is adapted to sense pressure fluctuations in the pumping chamber; a fluidic valve, operable to restrict fluid flow from the pumping chamber through the inlet; and a flow restrictor, operable to restrict fluid into the pumping chamber through the outlet, wherein the flow restrictor has an acoustic impedance approximately equal to the acoustic impedance of the fluid, so that reflection of sound from the flow restrictor is small relative to transmission of sound through the flow restrictor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A piezoelectric pump comprising:
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a pump housing; a movable diaphragm located within the pump housing and defining a pumping chamber within the pump housing, the pumping chamber having an inlet for admitting fluid into the pumping chamber and an outlet for emitting fluid; a piezoelectric transducer coupled to the moveable diaphragm and operable to move the diaphragm and thereby change the volume of the pumping chamber, wherein the piezoelectric transducer is adapted to sense pressure fluctuations in the pumping chamber, wherein the piezoelectric transducer is operable to generate a sound pulse in a fluid path downstream of the piezoelectric pump and to generate an electrical signal in response to reflections of the sound pulse; and further comprising a signal analyzer, electrically coupled to the piezoelectric transducer, for determining physical properties of the fluid from the electrical signal generated in response to reflections of the sound pulse. - View Dependent Claims (8, 9, 10)
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11. A method for sensing physical properties of a fluid path downstream of a piezoelectric pump, the pump having a pumping chamber bounded in part by a movable diaphragm activated by a piezoelectric transducer, the method comprising:
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applying an electrical excitation signal to the piezoelectric transducer to generate an acoustic pressure pulse in the fluid path downstream of a piezoelectric pump; sensing an electrical response signal produced by the piezoelectric transducer by reflections of the acoustic pressure pulse in the fluid path downstream of the piezoelectric pump; and analyzing the electrical response signal to determine physical properties of the fluid path downstream of the piezoelectric pump. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for measuring physical properties of a fluid delivery system having a piezoelectric pump, comprising:
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acoustically coupling a piezoelectric transducer of the piezoelectric pump to fluid in the fluid delivery system; generating a sound pulse in the fluid by applying an electrical excitation signal to the piezoelectric transducer; sensing an electrical response signal generated in the piezoelectric transducer by reflections of the sound pulse in the fluid delivery system; and analyzing the electrical response signal to determine physical properties of the fluid or the fluid delivery system. - View Dependent Claims (23, 24, 25)
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Specification