Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-01-05
2001-04-17
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S322000
Reexamination Certificate
active
06218768
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power ultrasonic transducer, and more particularly, to a power ultrasonic transducer which is used for the execution of ultrasonic cleaning, the promotion of chemical reaction and the like.
2. Discussion of Related Art
Generally, a conventional Langevin type transducer, which is configured to insert a piezoelectric element between two metals and to be secured by a bolt, has been widely used in this field. However, since this type of transducer can not be directly used in the water, it should be used only in case of being attached on a wall surface of a cleaning vessel. In addition, since the Langevin type transducer generates an ultrasonic wave by utilizing a longitudinal vibration, this results in the limitation of ultrasonic power generated from the transducer.
In the Langevin type transducer, hence, there occurs a disadvantage in that transducer array should be used so as to produce a high power. In this case, if these transducers are not synchronized with each other during operating period, the life of the adjacent transducers influenced by the distortion force generated from the vibration of any specific transducer can be shortened.
On the other hand, another research is executed by U.S. Pat. No. 4,537,511 (in 1985) which improves the above problems suffered from the conventional Langevin type transducer. This is an improved transducer which can produce a high power and is directly used in the water. In this effort, the transducer includes an ultrasonic generator which has a longitudinal vibration mode by using a piezoelectric element and a hollow type rod which has a length of integer(n) times of half wavelength(lambda/2) and is coupled to the end of one side of the ultrasonic generator, to thereby radiate the ultrasonic wave in a radial direction.
However, the transducer according to the U.S. Pat. No. 4,537,511 can produce a higher power, when compared with the conventional Langevin type transducer, but since the other end of the hollow type rod as a free end is exposed into a medium, an undesired ultrasonic wave in a longitudinal direction is radiated, which of course results in the loss of energy.
To solve this problem, another research is executed by U.S. Pat. No. 5,200,666 (in 1993) and European Pat. No. EP 455837 (in 1991), wherein a piezo type ultrasonic generator is attached on the both end sides of a hollow type rod, respectively, to thereby generate an higher ultrasonic power in a radial direction. Here, the hollow type rod has a length of integer(n) times of half wavelength(lambda/2), in the same manner as the above.
In this case, if the characteristics such as the resonant frequencies and impedances of the two end-sided ultrasonic generators are not accurately consistent with each other, there exists a difference in phases and amplitudes of the longitudinal vibration generated from each of the two ultrasonic generators, so the efficiency of the transducer is inevitably reduced. Meanwhile, upon manufacturing of the transducer, it is very difficult to make two ultrasonic generators have equal characteristics.
On the other hand,
FIG. 3
is a perspective view of a prior art transducer introduced by Uchino, which has a quite different structure and application from the conventional transducers as mentioned above. The disc-shaped transducer which is reported by Uchino in IEEE Vol. 44, No. 3,1997, pp. 597-605, 1997, is results in the increment of displacement thereof. In this effort, the shape of body (brass endcap) is newly designed, thus to allow the transducer to increase the ultrasonic power.
However, the transducer by Uchino takes a disc type having a diameter of about 10 mm and is used for a small actuator. Further, since the transducer includes the ultrasonic generator which is comprised only of a piezoceramic having about 1 mm in thickness and about 10 mm in diameter and utilizes a radial mode of the piezoceramic, it is apparent that it is difficult to manufacture the piezoceramic of the same thickness having about 50 mm or more in diameter. This results in a fundamental limitation in the increment of ultrasonic power from the transducer.
SUMMARY OF THE INVENTION
Accordingly, the present invention proposes a newly power ultrasonic transducer that substantially improves one or more of the problems due to limitations and disadvantages of the related arts.
An object of the invention is to provide the power ultrasonic transducer which is a rod type transducer used in the water for the ultrasonic cleaning of large capacity and the promotion of chemical reaction, includes a single ultrasonic generator to thereby solve the characteristic consistency problem generated upon the installation of two end-sided ultrasonic generator. The ultrasonic generator being comprised of a piezoceramic and a countermass, utilizes a thickness mode of the piezoceramic, increases the number of the piezoceramic to thereby increase the ultrasonic power and also the whole length(body length) thereof is extended from at least about 500 mm to the integer times of a half wavelength as a length of a transmitting rod is extended to integer times of a half wavelength, to thereby increase the ultrasonic power thereof.
To accomplish these objects, a power ultrasonic transducer includes an ultrasonic generator comprised of two pairs of piezoceramic elements which are adjoined to be coupled to each other on the same shaft and a countermass attached at the both ends of the piezoceramic elements; a hollow type body having a length of integer(n) times of half wavelength(lambda/2), in which the ultrasonic generator is positioned; a cylindrical transmitting rod having a length of integer(n) times of half wavelength (lambda/2) and for connecting the one side of the body with the one side of the ultrasonic generator to be fixed on the both sides of the ultrasonic generator, respectively; and a threaded stud for securing an electric wire for power supply at the one side end of the outside of the body, the electric wire for power supply passing through the countermass and the interior of the transmitting rod each positioned in the interior of the body to bewired to pass through the piezoceramic elements.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 2962695 (1960-11-01), Harris
patent: 4754441 (1988-06-01), Butler
patent: 4779020 (1988-10-01), Konno et al.
patent: 4996674 (1991-02-01), Thompson
patent: 5030873 (1991-07-01), Owen
patent: 5172344 (1992-12-01), Ehrlich
Heo Pil-Woo
Lee Yang-Lae
Lim Eui-Su
Arent Fox Kintner & Plotkin & Kahn, PLLC
Budd Mark O.
Korea Institute of Machinery & Materials
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