Fluent material handling – with receiver or receiver coacting mea – With signal – indicator – recorder – inspection means or exhibitor – Level or pressure in receiver
Reexamination Certificate
2000-11-02
2001-07-31
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
With signal, indicator, recorder, inspection means or exhibitor
Level or pressure in receiver
C141S083000, C141S067000, C073S715000, C029S621100
Reexamination Certificate
active
06267159
ABSTRACT:
BACKGROUND INFORMATION
German Patent Application No. 43 08 718, for example, describes that each of the two measuring chambers of a transducer measuring a pressure differential is filled through a filling channel after the respective measuring chamber has been evacuated. In filling each measuring chamber with the pressure transmission fluid, it is important to be sure that a defined volume of pressure transmission fluid be introduced into each measuring chamber. Each measuring chamber is gravity-filled with a pressure transmission fluid under vacuum. Then each filling channel is sealed by a sealing device which presses with a sealing ball on a ring lip on the outer end of the filling channel. The sealing ball is secured by a threaded pin.
Unexamined German Patent Application No. 20 38 868 describes another transducer measuring a pressure differential. For filling a measuring chamber with pressure transmission fluid, the pressure transmission fluid is filled into the measuring chamber under vacuum through a channel passing through a stopper after loosening a needle screw. With the help of the stopper, which can change positions due to its screwability and can be secured by a nut, the volume of the measuring chamber and thus the quantity of pressure transmission fluid can be adjusted.
SUMMARY
An object of the present invention is to provide a method of filling a measuring chamber of a transducer measuring a pressure or a pressure differential that can be carried out with a very precisely defined quantity of pressure transmission fluid in each measuring chamber. This object is achieved according to the present invention with a method of filling a measuring chamber of a transducer measuring a pressure or a pressure differential with a pressure transmission fluid through a filling channel, where a filling pin having a longitudinal channel over part of its total length is inserted at first into the filling channel far enough that an open connection of the measuring chamber to the outside remains. After evacuating the measuring chamber, the pressure transmission fluid which is under vacuum is introduced into the measuring chamber through the longitudinal channel and the filling channel under the influence of gravity and then to establish a defined working volume of pressure transmission fluid in the measuring chamber, a supplementary quantity of pressure transmission fluid is fed into the measuring chamber by pushing the filling pin beyond the end of its longitudinal channel.
One advantage of the method according to the present invention is that with it a very precisely metered amount of pressure transmission fluid can be introduced into the respective measuring chamber. This is due to the fact that the filling pin acts in the manner of a piston, so to speak, by “pushing” a precisely defined additional quantity of transmission fluid into the measuring chamber with its pushing action after the pressure transmission fluid has been introduced under gravity. Due to the design of the filling pin with a longitudinal channel and its mounting on the respective transducer in such a manner that there remains an open connection of the measuring chamber with the outside, it is ensured that evacuation and subsequent introduction of pressure transmission fluid under the influence of gravity will not be impaired. Thus, no additional process steps are necessary with the method according to the present invention in an advantageous manner (except for the final pushing of the filling pin) to introduce an additional quantity of pressure transmission fluid to a defined extent after introducing the pressure transmission fluid under the influence of gravity.
In the method according to the present invention, the filling pin can be secured in various ways in the area of the filling channel. However, for reasons pertaining to manufacturing technology and safety engineering, it maybe especially advantageous if the filling pin is secured by a weld after being pushed in.
The filling pin is advantageously pushed in until it is flush with the outer end of the filling channel, because then no reworking of the outside of the filling channel is necessary.
To be able to reliably “resupply” a defined volume of pressure transmission fluid when the filling pin is pushed in, the filling channel is advantageously provided with a sealing lip before introducing the filling pin.
Furthermore, the present invention relates a transducer measuring a pressure or a pressure differential having at least one measuring chamber which can be filled with a pressure transmission fluid through a filling channel and has a sealing device on the outer end of the filling channel. Such a transducer measuring a pressure or a pressure differential is described in, the German patent application described above.
To be able to fill such a transducer measuring a pressure or a pressure differential with a defined quantity of pressure transmission fluid in its measuring chamber or chambers, the sealing device includes according to the present invention filling pin which has a longitudinal channel over part of its total length and is pushed from a position leaving clear an opening to the measuring chamber into the filling channel after filling.
One advantage of the transducer according to the present invention is that it can be manufactured relatively easily with regard to the required filling with pressure transmission fluid and also contains a precisely metered amount of pressure transmission fluid in its measuring chambers.
With the transducer measuring a pressure or a pressure differential according to the present invention, the pin may have different designs of its longitudinal channel. It maybe advantageous if the longitudinal channel of the pin is formed by an outer flattened area on the pin parallel to its axis.
In another embodiment of the pin with regard to its longitudinal channel, the longitudinal channel is formed by a slot in the pin parallel to its axis.
REFERENCES:
patent: 4888992 (1989-12-01), Mathias et al.
patent: 5831170 (1998-11-01), Sokn
patent: 2 038 868 (1971-02-01), None
patent: 43 08 718 (1994-09-01), None
Patent Abstracts of Japan, vol. 014, No. 084 (P-1007) Feb. 16, 1990 & JP 01 296122A (Matsushita Electric Ind. Co. Ltd.), Nov. 29, 1989.
Patent Abstracts of Japan, vol. 097, No. 008, Aug. 29, 1997 & JP 09 101222A (Hitachi Ltd.) Apr. 15, 1997.
Adolf Sven
Metschke Hans-Michael
BakerBotts LLP
Douglas Steven O.
Siemens Aktiengesellschaft
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