US4383445A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitance circuit for level measurement
Assignee: INVALCO Inc
•
Filing: 1981-01-29
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Granted: 1983-05-17
•
Expires: 2001-01-29
Abstract
Abstract The circuit of a primary element capacitor is energized and arranged to produce a proximity signal not substantially affected by the conductivity of fluid-like material accumulated on the capacitor structure. The energization, circuit components, and capacitor insulation minimize the electrical characteristics of the material accumulation on the capacitor.
Inventors
- 👤 Leon S. Siegel
- 👤 Charles O. Holman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:35
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/26; G01F23/263; G01F23/266
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
166 words
An apparatus for detecting the level of a fluid-like material, comprising, a first primary element capacitor, having a first plate and a second plate, positioned to receive the rising level of fluid-like material in the space separating the first and second plates, a connection between the first plate of the first capacitor and ground, a source of periodically varying voltage, a fixed resistance connected between the voltage source and the second plate of the first capacitor, a voltage detector connected between the fixed resistance and the second plate of the first capacitor to manifest the voltage appearing at that junction, a second capacitor of substantially greater capacitance than the first capacitor connected in parallel with the first capacitor, the frequency of the voltage source and the value of the second capacitor being such as to give a capacitive reactance of the circuit of no more than one-tenth the value of resistance of the physical accumulation of the fluid-like material bridging the plates of the first capacitor.
Claim 2
Independent Claim
166 words
An apparatus for detecting the level of a fluid-like material, comprising, a first primary element capacitor, having a first plate and a second plate, positioned to receive the rising level of fluid-like material in the space separating the first and second plates, a connection between the first plate of the first capacitor and ground, a source of periodically varying voltage, a fixed resistance connected between the voltage source and the second plate of the first capacitor, a voltage detector connected between the fixed resistance and the second plate of the first capacitor to manifest the voltage appearing at that junction, a second capacitor of substantially greater capacitance than the first capacitor connected in parallel with the first capacitor, the frequency of the voltage source and the value of the second capacitor being such as to give a capacitive reactance of the circuit of no more than one-tenth the value of resistance of the physical accumulation of the fluid-like material bridging the plates of the first capacitor.
Claim 3
Dependent Claim
98 words
The apparatus of claim 1, including, an insulator body mounted in the space separating the two plates of the first primary element capacitor in the physical position to accumulate the fluid-like material whose level is being sensed and with the capacitance value of the insulator in series with the capacitance value of the accumulation of fluid-like material bridging the plates, whereby the equivalent capacitance of the insulator and the accumulation of fluid-like material bridging the plates is equal to less than the smaller of the two capacitance values and does not substantially alter the impedance of the circuit.
Claim 4
Dependent Claim
18 words
The apparatus of claim 1, wherein, the source of periodically varying voltage generates a sinusoidal form of voltage.
Claim 5
Dependent Claim
54 words
The apparatus of claim 1, wherein, the second plate of the first primary element capacitor is in the form of a rod and is arranged to be insulated from and to protrude horizontally from the first plate of the primary element capacitor which is in the form of a vessel receiving the fluid-like material.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-16 | 1986-11-15 | 1987-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-16 | 1990-11-15 | 1991-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-16 | 1994-11-15 | 1995-05-17 | $7700.00 | Window Closed / Lapsed |