A shield arrangement for a vacuum measuring cell has a tubular shield housing encompassing a shield and an exit port for connection to a vacuum measuring cell and a connection opening for the object space to be measured. The shield is between the two openings and is implemented as a screw shield wit
A shield arrangement for a vacuum measuring cell has a tubular shield housing encompassing a shield and an exit port for connection to a vacuum measuring cell and a connection opening for the object space to be measured. The shield is between the two openings and is implemented as a screw shield with spiral convolutions, its thread flange in the outer diameter being in contact on the inner wall of the shield housing such that a gas throughflow between the outer diameter of the thread flange and the inner wall is inhibited and is substantially forced into the spiral thread flight, and the exit port is on one side of the tubular section and the connection opening is on the other, opposite side and the screw shield is implemented such that in the axial line of vision the shield arrangement between the two openings is optically tight.
대표청구항▼
The invention claimed is: 1. A vacuum measuring cell (15) with a shield arrangement (25) for performing a protective function by decreasing contamination of the vacuum measuring cell in order to increase service life of the measuring cell while ensuring high measuring precision and reproducibility
The invention claimed is: 1. A vacuum measuring cell (15) with a shield arrangement (25) for performing a protective function by decreasing contamination of the vacuum measuring cell in order to increase service life of the measuring cell while ensuring high measuring precision and reproducibility of vacuum measurement, the vacuum measuring cell comprising: a measuring cell housing (1, 4) with a diaphragm (2) for measuring a vacuum, a shield housing encompassing a shield, the shield housing being outside the measuring cell housing and having an exit port (16) with an exit opening connected to the measuring cell housing and a connection opening (22) for connection with an object space to be measured, and the shield being disposed between the openings (16, 22), the shield housing comprising a tubular section (14) and the shield (7, 20) in the tubular section, the shield comprising a screw shield (20) with spiral convolutions (21) defining a spiral path with a cross section, the convolutions having at least one thread flange with an outer diameter in contact with an inner wall of the tubular section (14) so that in an axial line of vision between the openings, the shield is optically tight so as not to permit any through-view between the openings and such that a gas throughflow between the outer diameter of the thread flange and the inner wall is inhibited and such throughflow is forced substantially only into the spiral path, the exit port (16) being on the one side of the tubular section (14) and the connection opening (22) being on the other opposite side of the tubular section, the shield arrangement with its spiral path decreasing contamination of the vacuum measuring cell, and the cross section of the spiral path being larger than a cross section of all solid material of the screw shield so that a favorable ratio of spiral path cross section to solid material cross section is provided for improving the protective function of the shield arrangement and to improve measuring performance of the vacuum measuring cell. 2. A vacuum measuring cell as claimed in claim 1, wherein the screw shield (20) has at least 1.5 convolutions (21). 3. A vacuum measuring cell as claimed in claim 2, wherein the screw shield (20) is a multi-flight screw (20). 4. A vacuum measuring cell as claimed in claim 1, wherein the screw shield (20) is a flat-flight screw (20). 5. A vacuum measuring cell as claimed in claim 1, wherein the screw shield (20) comprises a rod core (23) about which the spiral convolutions are disposed. 6. A vacuum measuring cell as claimed in claim 1, wherein the length (l) of the screw shield (20) is greater than its outer diameter (2r). 7. A vacuum measuring cell as claimed in claim 1, wherein the tubular section (14) includes on the connection opening (22) a connection flange (8) and is formed together with the tubular section (14) of one piece. 8. A vacuum measuring cell as claimed in claim 1, wherein in the proximity of the exit port (16) a circular flat shield (30) is disposed which is as a screening shield (30). 9. A vacuum measuring cell as claimed in claim 8, wherein the flat shield (30) is fixed on the screw shield (20). 10. A vacuum measuring cell as claimed in claim 9, wherein the flat shield has retaining links (33) on its periphery for the fixing on the inner wall of the tubular section (14). 11. A vacuum measuring cell as claimed in claim 1, wherein the screw shield (20) is made so that it can be slid into the tubular section (14) and pulled out of the tubular section. 12. A vacuum measuring cell as claimed in claim 1, wherein the shield arrangement (14, 20, 25) is connected to the measuring cell housing via the exit port (16) and the vacuum measuring cell includes the diaphragm in the measuring cell housing, the vacuum measuring cell comprising one of a capacitive diaphragm measuring cell and an optical diaphragm measuring cell.
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이 특허에 인용된 특허 (6)
Sharpless, Leonard J.; Benjamin, Neil; Fish, Jeffrey W., Capacitive manometer having reduced process drift.
Rosenstein Michael (Sunnyvale CA) Grunes Howard (Santa Cruz CA) Brodsky Stephen Bruce (Fishkill NY), Screwless shield assembly for vacuum processing chambers.
Ferran, David J.; Ferran, Robert J., Apparatus and method for automatic detection of diaphragm coating or surface contamination for capacitance diaphragm gauges.
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