Pumps – Motor driven – Magnetostrictive chamber
Reexamination Certificate
2002-04-09
2004-06-15
Yu, Justine R. (Department: 3746)
Pumps
Motor driven
Magnetostrictive chamber
C040S006000, C040S413000
Reexamination Certificate
active
06749406
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ultrasonic pump for pumping a non-solid medium or fluid, such as a liquid, a liquid metal, a gas or an aerosol, via absorption by the medium of non-planar focused ultrasonic longitudinal waves directly generated by a single- or broad-bandwidth, non-planar transducer.
BACKGROUND OF THE INVENTION
There are many types of electromechanical pumps utilized today to pump fluids, such as gear pumps, centrifugal pumps, roller pumps, piston and peristaltic pumps, all of which require moving parts for proper operation. Typically, these moving parts are designed in relation to the amount of fluid to be pumped per unit time and the overall volume of the physical pump design.
Piston pumps are generally defined as having rotating pistons of varying stroke lengths to pump fluid media through check valves. Because piston pumps are capable of generating great pressure, they are suitable for high pressure applications. Nevertheless, piston pumps require many moving parts such as a piston, piston rod, crankshaft, and associated valve assemblies.
Peristaltic pumps are generally defined as having rollers driven by a motor which push a fluid medium along the internal diameter of tubing as the rollers are rotated by the motor. Peristaltic pumps are considered safe, mainly because the pumped the fluid medium never contacts an environment different than the surfaces of the internal tubing. They are used widely in the medical and pharmaceutical sector where the prevention of contamination is a factor. One major disadvantage associated with peristaltic pumps lies in the possible crushing forces that result upon the fluid medium being pumped, in those instances where the tubing constricts completely. Moreover, the moving parts of the peristaltic pumps usually undergo fatigue, as a result of their continuous operation and this can result in particles being shed from the tubing.
There are also for consideration the operation of sonic and ultrasonic pumps that feature as an embodiment the use of acoustic waves for their principle of operation, for example,. Mandroian U.S. Pat. No. 3,743,446, Lucas U.S. Pat. No. 5,020,977, and Lucas U.S. Pat. No. 5,263,341, Haller et al., U.S. Pat. No. 6,010,316, Culp, U.S. Pat. No. 5,267,836, Oeftering, U.S. Pat. No. 6,029,518, Oeftering, U.S. Pat. No. 5,520,715, Oeftering, U.S. Pat. No. 6,003,388, Murphy, U.S. Pat. No. 4,753,579, Murphy, U.S. Pat. No. 4,684,328, Kamen et al., U.S. Pat. No. 5,349,852, Meise, U.S. Pat. No. 5,295,791, White, et al., U.S. Pat. No. 5,212,988, Keilman, U.S. Pat. No. 4,475,376, Haller and Khuri-Yakub, U.S. Pat. No. 6,010,316, Masahiro, JP 550005454A2, Kazuo, et al., JP 62191679A2, and Kawai, et al., JP 5079459A2.
Referring to U.S. Pat. No. 3,743,446, invented by Mandroian, it uses a source of sound from a fluctuating diaphragm or piezoelectric transducer that oscillates at a preselected frequency. The frequency of oscillation of the diaphragm piezoelectric transducer and the length of the pump chamber are configured together so that this arrangement forms a resonant cavity (chamber) where acoustic standing waves are established in the fluid which allows for a pressure node or antinode at the wall opposite the diaphragm piezoelectric transducer.
Referring now to U.S. Pat. Nos. 5,020,947 and 5,263,341, each invented by Lucas, the theory of operation and so with the basic embodiment of both patents acknowledges the objective of using standing waves of acoustic pressure for creating nodes which are periodic points of minimum pressure and antinodes which are periodic points of maximum pressure. These nodes and antinodes are required to be precisely located at the entrance and exit fluid ports and, thus, the standing wave phenomenon as relied upon in Lucas requires a resonant state for proper operation. Moreover, the compressors in the Lucas patents require that a very narrow resonant operational frequency range be utilized by way of special electronic control circuitry, which includes a microprocessor controlled phase locked loops to insure frequency stability, thus adding to the complexity of the design. Such control circuitry is necessary for such a complex compressor system used for refrigeration.
Thus, the essence of the compressors described in the Lucas' patents require the creation of a standing wave within a resonant chamber or cavity and attempts to maintain the standing wave with its fixed periodic nodes and antinodes of pressure.
Turning now to U.S. Pat. No. 5,349,852, invented by Kamen et al., it describes a method of controlling a pump by using an acoustically resonant chamber driven by a loudspeaker to measure the volume of fluid in the chamber. There is no acoustic aspect to the pumping action and, in fact, this method of pump control could be applied to virtually any type of pump.
U.S. Pat. No. 5,378,120, invented by Taig, concerns a piezoelectric pump, not an ultrasonic pump. A stack of piezoceramic material is driven with a voltage to produce a volume displacement of fluid in a chamber. The piezoelectric stack is driven at a low (probably sonic) frequency to resonate a diaphragm which also acts as a check valve for the pump. This pump does not produce or rely upon ultrasonic waves or momentum transfer from the waves to the fluid.
U.S. Pat. No. 5,295,791, invented by Meise, concerns a low-frequency device wherein an acoustic resonance is established in a gas within a tube. Pressure differences at nodes and anti-nodes are used to advantage for refrigeration because there is a temperature differential between the two. This type of device has much in common with an organ pipe or a musical instrument, where a resonant tube is used to produce sound, except here they are using the structure in reverse: sound is applied, and a temperature difference results.
U.S. Pat. No. 5,212,988, invented by White, et al., describes the basic principles of a SAW sensor. These devices operate typically at several hundred MHz. A Lamb wave (a type of surface wave) is generated on the surface of a plate. The plate is coated with a polymer that is sensitive to the desired substance; usually, it absorbs the material, and changes its mass. The Lamb wave velocity and attenuation are affected by the changing properties of the polymer “sensor” film, and so you measure the Lamb wave and infer what is being sensed by the film.
Japanese Patent Document No. 62191679A2, authored by Kazuo, et al., concerns a “resilient” plate, such as possibly rubber, attached to a tapered end of a horn-type transducer. These devices typically operate in the range of 10 to 30 kHz. Basically, this is a diaphragm-type pump, where the diaphragm is being driven by an ultrasonic horn transducer. Nevertheless, the pumping action is mechanical and is unrelated to any acoustic waves that it might also produce in the fluid.
Japanese Patent Document No. 5079459A2, authored by Kawai, et al., appears to describe an ultrasonic motor which is being used to drive a micropump. The motor seems to function by producing a vibration in a plate which travels in a circle and causes a rotating element to turn in one direction, and are quite common in many items such as camera lenses. This is a low-frequency (audio range) device.
U.S. Pat. No. 4,475,376, invented by Keilman, describes an ultrasound transducer testing device. It has a focused ultrasonic transducer at the large end of a fluid-filled conical chamber, which tapers down to a small opening at the other end.
U.S. Pat. No. 6,010,316, invented by Haller and Khuri-Yakub, concerns an ultrasonic micro pump which describes a planar transducer and requires a simple high-velocity plano-concave lens to focus the ultrasonic waves generated by a transducer. The lens described by Haller et al is limited because of its material properties (silicon nitride, density 3.27 g/cm
3
, longitudinal sound velocity of about 11,000 m/sec and an impedance of 36.0 Mrayls). Apparently, this material was used because it is easily achieved on a silicon wafer. It is, however, an extremely poor choice acoustically because of
Belena John F.
Harness & Dickey & Pierce P.L.C.
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