Patent US4590797A successfully refreshed from Google Patents.
US4590797A
Expired / Lapsed
US
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Thermal system for measuring liquid levels
Assignee: Areva NP SAS
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Filing: 1984-09-24
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Granted: 1986-05-27
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Expires: 2004-09-24
Abstract
Abstract A thermal liquid level measuring system including a heat sensor with a sheathed heating resistor and a measuring resistor. Power is supplied to the heating resistor in a series of pulses. The measuring resistor is connected to two filters which extract the a.c. and d.c. components from the measuring signal. A temperature measuring device determines the difference in temperature of the liquid and the gas above the liquid. A computer receives signals from the filters and the temperature measuring device to determine the level of the liquid and its temperature.
Inventors
- 👤 Jean Beaubatie
- 👤 Francois Cavarec
- 👤 Jean-Francois Lenclos
- 👤 Marc Paris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:42
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/246; Y; Y10; Y10T; Y10T137/00; Y10T137/7287; Y10T137/7306
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
216 words
A thermal system for measuring a liquid level comprising a heat sensor with a measuring resistor (2) and a sheathed (1) heating resistor (3), said heating resistor receiving a pulsed power input, wherein the temperature variation of said heat sensor during the immersion of said heat sensor in liquid (11) is used for determining said liquid level, characterized in that it comprises a matching circuit (18) measuring the voltage at terminals (7, 8) of the measuring resistor (2), the measuring resistor being supplied by a constant current supply (17), the output of said matching circuit being connected in parallel to an input of each of two filters (20, 22) for respectively extracting a d.c. component and an a.c. component of the measuring signal, the measuring signal being at the same frequency as said pulsed power input, a computing module (29), in which the value of the level of the liquid and its temperature are determined on the basis of output signals from filters (20, 22) and a signal supplied by a means for measuring the variation of the temperatures of the liquid and gaseous medium above the liquid, said computing module (29) producing a liquid level signal on the basis of the first derivative with respect to time of the a.c. component of the measuring signal.
Claim 2
Dependent Claim
216 words
A thermal system for measuring a liquid level comprising a heat sensor with a measuring resistor (2) and a sheathed (1) heating resistor (3), said heating resistor receiving a pulsed power input, wherein the temperature variation of said heat sensor during the immersion of said heat sensor in liquid (11) is used for determining said liquid level, characterized in that it comprises a matching circuit (18) measuring the voltage at terminals (7, 8) of the measuring resistor (2), the measuring resistor being supplied by a constant current supply (17), the output of said matching circuit being connected in parallel to an input of each of two filters (20, 22) for respectively extracting a d.c. component and an a.c. component of the measuring signal, the measuring signal being at the same frequency as said pulsed power input, a computing module (29), in which the value of the level of the liquid and its temperature are determined on the basis of output signals from filters (20, 22) and a signal supplied by a means for measuring the variation of the temperatures of the liquid and gaseous medium above the liquid, said computing module (29) producing a liquid level signal on the basis of the first derivative with respect to time of the a.c. component of the measuring signal.
Claim 3
Dependent Claim
26 words
Thermal measuring system according to claim 1, characterized in that the two filters (20, 22) are controlled by pulse signals produced by a logic module (15).
Claim 4
Dependent Claim
16 words
Thermal measuring system according to claim 1, characterized in that the temperature measuring means are thermocouples.
Claim 5
Dependent Claim
17 words
Thermal measuring system according to claim 1, characterized in that the temperature measuring means are resistance probes.
Claim 6
Dependent Claim
32 words
Thermal measuring system according to claim 1, characterized in that the temperature measuring means are resistance probes, which are heated at the same frequency and in phase with said pulsed power input.
Claim 7
Dependent Claim
136 words
Thermal measuring system according to claim 1, wherein said computing module comprises two computing circuits and two integrators, each of said two computing circuits receiving a first input from the corresponding one of said two filters, a second input receiving said signal supplied by said means for measuring the variation of the temperatures, and third and fourth inputs connected to the outputs of said two integrators, the input to each integrator being the sum of a first output signal from one of the two computing circuits and a second output signal from the other of said two computing circuits, said inputs to said integrators representing the time derivatives of the liquid level and the liquid temperature, said computing module using the method of least squares by iterating the values of the liquid temperature and liquid level.
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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) | 1989-05-26 | 1989-11-25 | 1990-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-26 | 1993-11-25 | 1994-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-26 | 1997-11-25 | 1998-05-27 | $7700.00 | Window Closed / Lapsed |