Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1998-12-23
2002-04-09
Yuen, Henry C. (Department: 3747)
Pumps
Motor driven
Electric or magnetic motor
C417S053000
Reexamination Certificate
active
06368079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention pertains to the art of methods and apparatuses for pumping fluid from a container to a delivery point in low volumes and at controlled flow rates, and more specifically to methods and apparatuses for using a piezoelectric driven pump to control the delivery of a fluid, such as a pharmaceutical solution or suspension, from a container to a delivery point.
2. Description of the Related Art
Numerous fluidics applications in such areas as medicine, chemistry, and environmental testing exist on a small scale for reasons of sample size, reagent costs, or portability. Cost-effective fluidics components, including pumps, that are capable and reliable are required for such small scale systems. Current pump designs are typically based on valves that open and close. Such valves tend to be direct applications of designs that work in macroscopic apparatuses, but are not necessarily the best choice for microapplications. These apparatuses require valve seats or other types of sealing and anti-seizure mechanisms, and typically are limited to fully-opened clearances that are relatively small.
A number of micropumps exist for delivering small amounts of a fluid to a delivery point. Some of the pumps include a piezoelectric element, which changes its dimensions when it is stressed electrically by a voltage. U.S. Pat. No. 4,938,742 to Smits describes a micropump with piezoelectric valves. These valves contain a diaphragm covered by a single layer of piezoelectric material, which limits the control and deflection possibilities of the valves.
U.S. Pat. No. 5,611,676 to Ooumi et al. shows the use of a cantilevered piezoelectric bimorph. A piezoelectric bimorph has two layers of a piezoelectric material separated by a shim. The application of an electric field across the two layers of the bimorph causes one layer to expand while the other contracts. The net result is a curvature much greater that the length or thickness deformation of the individual layers. However, the micropump of Ooumi et al. uses the piezoelectric bimorphs only as single function seals for opening and closing openings or as single function pumps, not as multifunctional seals and pumps.
The present invention contemplates a new and improved piezoelectric micropump that is simple in design, effective in use and compact. The new and improved piezoelectric micropump provides increased fluid flow rates with low power consumption. It overcomes the foregoing difficulties and others while providing better and more advantageous overall results.
SUMMARY OF THE INVENTION
In accordance with the present invention, a new and improved piezoelectric micropump is provided that pumps fluid from a container to a delivery point in small and precise amounts or at controlled flow rates.
According to one aspect of the present invention, a micropump for pumping a fluid from a fluid container to a delivery point is disclosed that includes a pump body. A passageway extends through the pump body from the fluid container to the delivery point. The pump body has first, second, and third cavities intersecting with the passageway. A first diaphragm covers the first cavity and opens and closes the passageway as the first diaphragm is raised and lowered. A first diaphragm clamp secures the first diaphragm to the pump body. A first cantilevered piezoelectric actuator raises and lowers the first diaphragm. The first cantilevered piezoelectric actuator has a first end and second end, the first end being operatively connected to the first diaphragm. A first actuator clamp secures the second end of the first cantilevered piezoelectric actuator to the pump body. A second diaphragm covers the second cavity and opens and closes the passageway as the second diaphragm is raised and lowered. A second diaphragm clamp secures the second diaphragm to the pump body. A second cantilevered piezoelectric actuator raises and lowers the second diaphragm. The second cantilevered piezoelectric actuator has a first end and second end, the first end being operatively connected to the second diaphragm. A second actuator clamp secures the second end of the second cantilevered piezoelectric actuator to the pump body. A third diaphragm covers the third cavity. The third diaphragm opens and closes the passageway as the third diaphragm is raised and lowered. The third diaphragm is secured to the pump body by the first diaphragm clamp. A third cantilevered piezoelectric actuator raises and lowers the third diaphragm. The third cantilevered piezoelectric actuator has a first end and second end, the A first end being operatively connected to the third diaphragm, the second end of the third cantilevered piezoelectric actuator being secured to the pump body by the first actuator clamp. An electronic control circuit supplies voltages to the first, second, and third cantilevered piezoelectric actuators for raising and lowering the first, second, and third diaphragms at predetermined intervals, thereby promoting a flow of the fluid through the passageway.
According to another aspect of the present invention, a micropump for pumping a fluid from a fluid container to a delivery point is disclosed which includes a pump body having a passageway therethrough from the fluid container to the delivery point. The pump body has first and second cavities intersecting with the passageway. A first diaphragm covers the first cavity. The first piezoelectric actuator has a first end and second end, the first end being operatively connected to the first diaphragm. The first diaphragm opens and closes the passageway as the first diaphragm is raised and lowered in response to a first piezoelectric actuator. A second diaphragm covers the second cavity. The second diaphragm opens and closes the passageway as the second diaphragm is raised and lowered. A securing apparatus secures the first and second diaphragms to the pump body. A second piezoelectric actuator raises and lowers the second diaphragm. The second piezoelectric actuator has a first end and second end, the first end being operatively connected to the second diaphragm. The second ends of the first and second piezoelectric actuators are secured to the pump body with the first ends of the actuators being cantilevered from the pump body. An electrical apparatus applies voltages to the first and second piezoelectric actuators causing the first and second piezoelectric actuators to raise and lower the first and second diaphragms at predetermined intervals.
According to another aspect of the present invention, the micropump pump body has a third cavity intersecting with the passageway. The micropump further includes a third diaphragm covering the third cavity. The third diaphragm opens and closes the passageway as the third diaphragm is raised and lowered. The third diaphragm is secured to the pump body by the securing apparatus. A third piezoelectric actuator raises and lowers the third diaphragm. The third piezoelectric actuator has a first end and second end, the first end being operatively connected to the third diaphragm. The second end of the third piezoelectric actuator is secured to the pump body by the cantilever securing apparatus. The electrical apparatus applies a voltage to the third piezoelectric actuator causing the third piezoelectric actuator to raise and lower the third diaphragm.
According to another aspect of the present invention, a micropump for pumping a fluid from a fluid container to a delivery point is disclosed which includes a pump body. The pump body has a passageway therethrough from the fluid container to the delivery point. The pump body has first and second cavities intersecting with the passageway. A first pumping apparatus opens and closes the passageway at the first cavity and creates a vacuum for promoting the flow of the fluid through the passageway. A first piezoelectric actuator actuates the first pumping apparatus. A second pumping apparatus opens and closes the passageway at the second cavity and creates a vacuum for promoting the flow of the fluid through th
Bouton Chad E.
Peters Richard D.
Zimlich, Jr. William C.
Battelle Pulmonary Therapeutics, Inc.
Gimie Mahmoud
Porter Wright Morris & Arthur
Yuen Henry C.
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