Motors: expansible chamber type – With motive fluid valve
Reexamination Certificate
1999-05-20
2001-05-15
Ryznic, John E. (Department: 3745)
Motors: expansible chamber type
With motive fluid valve
C251S208000, C251S344000, C251S345000
Reexamination Certificate
active
06230607
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an adjusting device for a pneumatic drive, particularly a pneumatic drive of a medical or dental instrument, for example, a handpiece or angle piece, which delivers its energy by vibration and in which the vibrations are produced by a pneumatic drive.
2. Description of the Related Art
In the past, pneumatically driven vibration systems have been offered by only two companies who own the corresponding patents. The manufacturers of instruments obtain these systems from the two companies and, until recently, mounted them exclusively in so-called scalers which are devices for removing tartar.
In the year 1992, it was recognized that it is possible by means of such vibrating tools with appropriately configured tool surfaces (covered with diamond chips, etc.) to also remove teeth or bones or other hard materials. This was disclosed in DEG 92 17 943.6 U1.
A further development of this concept is disclosed in WO96/14024A. A shaping tool is placed on such a conventional scaler with produces in a tooth a negative shape of the tool. The removal of the material is effected by the oscillations of the shaping tool and, thus, the size of the removed area is essentially larger than the tool by an extent which corresponds to this oscillation amplitude. Since the oscillation amplitude is extremely small, recesses are formed which are dimensionally very accurate, which may be defined by sharp edges and which significantly deviate from the round cross-section.
These types of recesses in a tooth are required for prefabricated tooth replacement materials which are standardized with respect to shape, such as inlays. The replacement materials have at the appropriate locations precisely formed and shaped projections which fit into the recesses produced in the above-described manner and are glued or cemented into the recesses.
Other applications relate to the root canal treatment and the cleaning of the tooth surface with oscillating brushes. For carrying out these treatments, it is also possible to use instruments which have a pneumatic drive. Of course, air flows for other apparatus and devices also require a control, usually within wide limits; however, the control still has to be sensitive.
It has now been found that the material removal capacities and the oscillation amplitudes vary substantially in one and the same instrument in dependence on the tool placed on the drive. We have found that the reason for this is the fact that the oscillation behavior of the tool, the tool shaft and the pneumatic vibration drive forms a complicated oscillation system and the maximum material removal capacity and dimensional accuracy of the formed recess in various tools or applications are due to the respectively different air flows to the pneumatic vibration drive.
Therefore, the present invention relates to an adjusting device for a pneumatic vibration drive in a dental or medical instrument of the above-described type.
An adjusting device of this type is used in practice and is composed of an adjusting sleeve arranged on the handpiece, wherein a rotation of the adjusting sleeve causes a Teflon block to close the drive air line to a different extent. This control is extremely inaccurate and not linear.
A later adjusting device by the same manufacturer, wherein the configuration thereof is unknown, includes an adjusting sleeve which can be rotated by approximately four full rotations relative to the center axis of the handpiece for moving the sleeve between the position fully closed and the position fully open. However, this adjusting device is completely useless for the purpose of the present invention because the physician using the adjusting device cannot determine the present position of the adjusting device; this determination cannot even be made when the instrument is idling in the air because the oscillation behavior of the above-described oscillating system in the unloaded state differs significantly or may differ from the behavior in the loaded state and even an experienced user cannot find any indication concerning the adjustment of the adjusting device.
Moreover, the device known in the art is in spite of a large adjusting distance entirely incapable of exhibiting an even approximate linear behavior, so that there are adjusting ranges in which even a small rotation of the adjusting sleeve results in a substantial change of the air flow, while in another range even a substantial rotation of the adjusting sleeve produces only a slight change of the air flowing through.
SUMMARY OF THE INVENTION
Consequently, it is the object of the present invention to provide an adjusting device in which the disadvantages of the previously known adjusting devices are eliminated and which is capable of indicating clearly to the user prior to the start of operation of the instrument in a clear and simple manner the position of the adjusting device.
In accordance with the present invention, an air flow is controlled by having an air supply line and an air discharge line end at a distance from each other at a surface and by providing a counter-surface which is movable relative to the surface and, which, in dependence of its position relative to the surface, forms a flow path with a defined flow resistance between the air supply line and the air discharge line.
More specifically, the above-described object is met in a device of the above-described type in that the adjusting device is composed of an adjusting ring rotatably mounted on the handpiece, wherein the adjusting ring is rotatable by less then 360° about the axis of the handpiece. The adjusting ring has at its essentially circular cylindrical inner wall surface a recess which has a continuously changing cross-section in the circumferential direction. At least one drive air supply line extends in the handpiece essentially radially outwardly and a drive air transfer line extends in the handpiece essentially radially inwardly starting from the inner wall surface of the adjusting ring toward the air-driven vibration drive, wherein, depending on the angular position of the adjusting ring relative to the handpiece, the recess of the adjusting ring is located to a greater or lesser extent opposite the end of the air supply line and/or opposite the end of the air discharge line.
As a result of the configuration according to the present invention, it is achieved that based on its angular position the adjusting ring provides a clear indication of the adjustment of the adjusting device; this can be made even clearer by providing appropriate markings at the adjusting ring and at the handpiece body.
In accordance with a further development of the invention, several markings may be provided which serve as indications for the user for the respectively best adjustment for a predetermined manner of operation.
In accordance with another feature, it is also possible to find particularly important positions more easily by a conventional locking mechanism, so that reaching of the correct position can be heard or felt.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 2911008 (1959-11-01), Du Bois
patent: 3033226 (1962-05-01), Allen
patent: 5123449 (1992-06-01), Nowicki
patent: 5148830 (1992-09-01), Liu
patent: 5332194 (1994-07-01), Austin, Jr. et al.
patent: 5782455 (1998-07-01), Burnworth
patent: 9217943 (1993-07-01), None
patent: 96/14024 (1996-05-01), None
Brugger Wilhelm
Kardeis Richard
Rehrl Gregor
Dentalwerk Burmoos Gesellschaft m.b.H.
Kueffner Friedrich
Ryznic John E.
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