US3628136A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Means for measuring clearances in a gas turbine including a coaxial cable capacitor
Assignee: Garrett Corp
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Filing: 1969-09-05
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Granted: 1971-12-14
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Expires: 1989-09-05
Abstract
Abstract This apparatus for measuring rapidly changing clearances between relatively movable machine parts in high-temperature regions has a variable capacitor, formed by a stationary electrode and a certain part of the machine movable relative thereto, connected in a circuit having a relatively fixed capacitor provided by a coaxial cable the center conductor of which constitutes a lead to the electrode, a source of high-frequency excitation voltage, a voltage divider, a transistor, a load resistor, and suitable means for translating variations in capacitance of the variable capacitor due to relative movement of the machine parts into indications of measurement of the spacing between the machine parts.
Inventors
- 👤 Robert P Jonas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:56
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
185 words
Means for measuring operating clearance between two spaced relatively movable elements in a structure, comprising: a. a first capacitor having the first of said elements as one plate and an electrode mounted on and insulated from the second element as the other plate; b. a second capacitor consisting of a coaxial cable having first and second coextending metallic conductors electrically insulated from one another as the capacitor plates, the first of said conductors being electrically connected at one end with said electrode; and c. circuit means having an excitation oscillator with one terminal connected with the second conductor of said second capacitor and the other terminal connected with said one plate of said first capacitor, a voltage divider with a pair of resistors in series connected with the terminals of said oscillator, and means connected with the other end of the first conductor of said second capacitor and the junction between the resistors of said voltage divider for indicating differences in voltage between such points of connection resulting from variations in capacitance in said first capacitor caused by changes in clearance between said movable elements.
Claim 2
Dependent Claim
185 words
Means for measuring operating clearance between two spaced relatively movable elements in a structure, comprising: a. a first capacitor having the first of said elements as one plate and an electrode mounted on and insulated from the second element as the other plate; b. a second capacitor consisting of a coaxial cable having first and second coextending metallic conductors electrically insulated from one another as the capacitor plates, the first of said conductors being electrically connected at one end with said electrode; and c. circuit means having an excitation oscillator with one terminal connected with the second conductor of said second capacitor and the other terminal connected with said one plate of said first capacitor, a voltage divider with a pair of resistors in series connected with the terminals of said oscillator, and means connected with the other end of the first conductor of said second capacitor and the junction between the resistors of said voltage divider for indicating differences in voltage between such points of connection resulting from variations in capacitance in said first capacitor caused by changes in clearance between said movable elements.
Claim 3
Dependent Claim
59 words
Means for measuring operating clearance between two spaced elements as defined in claim 1 in which the means for indicating differences in voltage resulting from variations in capacitance in the first capacitor has a transistor with the base thereof connected with the other end of the first conductor of said second capacitor for conditioning signals generated in said circuit.
Claim 4
Dependent Claim
33 words
Means for measuring operating clearance between two spaced elements as defined in claim 2 in which the emitter of said transistor is connected to the junction between the resistors of said voltage divider.
Claim 5
Dependent Claim
74 words
Means for measuring operating clearance between two spaced elements as defined in claim 1 in which the values of the resistors of said voltage divider provide a ratio in excess of the capacitance ratio of the second capacitor to the first capacitor so that for all changes in value of the first capacitor a significant imbalance in voltage always exists between the junction between said resistors and the inner conductor of said second capacitor.
Claim 6
Dependent Claim
31 words
Means for measuring operating clearance between two spaced elements as defined in claim 3 in which a power source is connected through a load resistor with the collector of the transistor.
Claim 7
Dependent Claim
33 words
Means for measuring operating clearance between two spaced elements as defined in claim 5 in which a transducer is connected at the juncture of said load resistor and the collector of the transistor.
Claim 8
Dependent Claim
29 words
Means for measuring operating clearance between two spaced elements as defined in claim 6 in which the indicating means has rectifying, filtering, amplifying, and demodulating equipment in circuit therewith.
Claim 9
Dependent Claim
43 words
Operating clearance measuring means as defined in claim 1 in which the spaced elements of the structure are a turbine wheel and shroud of a gas turbine engine and the metallic conductors of the second capacitor are electrically insulated by a heat-resistant material.
Claim 10
Dependent Claim
28 words
Operating clearance measuring means as defined in claim 8 in which the material electrically insulating the metallic conductors of the second capacitor from one another is magnesium oxide.
Claim 11
Dependent Claim
42 words
Operating clearance measuring means as defined in claim 8 in which the metallic conductors of the second capacitor are parts of a coaxial cable spaced by a material having heat-resisting and electrical insulating characteristics equal at least to those of magnesium oxide.
Claim 12
Dependent Claim
38 words
Operating clearance measuring means as defined in claim 8 in which the turbine wheel constitutes the first of said spaced elements and is electrically connected with the second terminal of the oscillator via the frame of the structure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-13 | 1975-06-14 | 1975-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-13 | 1979-06-14 | 1979-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-13 | 1983-06-14 | 1983-12-14 | $7700.00 | Window Closed / Lapsed |