US3580074A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature-compensated liquid quantity gage
Assignee: TRANS SONICS Inc
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Filing: 1969-05-23
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Granted: 1971-05-25
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Expires: 1989-05-23
Abstract
Abstract A temperature sensor comprises the usual ''''hot'''' thermocouple junction exposed to the temperature to be monitored, a reference junction, a thermally sensitive resistor connected to compensate for changes in the temperature of the reference junction and a readout unit that converts the outputs of these elements to a temperature indication. The reference junction and the resistor are located in the probe that contains the hot junction, so that the leads extending from the probe to the readout unit need not be made of the materials of which the thermocouples are made. The thermally sensitive resistor is in series with the hot junction and reference junction. This permits the use of a single pair of leads to carry current for the resistor and, at the same time, bring back to the readout unit a net voltage comprising the thermocouple junction voltages and the compensating voltage from the resistor. A capacitive-type liquid quantity gage extending partway down into a tank includes a capacitive liquid level sensor and a temperature sensor positioned to sense the temperature of the liquid monitored by the level sensor. The output of the temperature sensor controls the drive voltage to the level sensor so as to compensate for changes in density and dielectric constant resulting from temperature changes in the liquid. The resulting compensated signal is further adjusted by subtracting from it a signal derived from the temperature sensor to account for expansion or contraction of the liquid below the bottom of the level sensor.
Inventors
- 👤 Vernon C Wescott
- 👤 Sidney B Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:22
CPC Classifications
G; G01; G01K; G01K7/00; G01K7/02; G01K7/021; G01F; G01F23/00; G01F23/22; G01F23/26; G01F23/263; G01F23/266
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
132 words
A liquid mass gauge comprising A. a capacitive liquid sensor having first and second electrodes, B. an alternating current generator connected to said first electrode so as to pass a current through said sensor, C. a rectifier connected to said second electrode so as to rectify said sensor current, D. a temperature sensor arranged to provide a temperature signal corresponding to the temperature of the liquid monitored by said liquid sensor, and E. means applying said temperature signal to said generator to vary the output of said generator by an amount proportional to the variation in volume of said liquid due to temperature changes so as to maintain said sensor current substantially independent of changes in the temperature of the liquid above the bottom of the sensor before and after temperature changes.
Claim 2
Dependent Claim
132 words
A liquid mass gauge comprising A. a capacitive liquid sensor having first and second electrodes, B. an alternating current generator connected to said first electrode so as to pass a current through said sensor, C. a rectifier connected to said second electrode so as to rectify said sensor current, D. a temperature sensor arranged to provide a temperature signal corresponding to the temperature of the liquid monitored by said liquid sensor, and E. means applying said temperature signal to said generator to vary the output of said generator by an amount proportional to the variation in volume of said liquid due to temperature changes so as to maintain said sensor current substantially independent of changes in the temperature of the liquid above the bottom of the sensor before and after temperature changes.
Claim 3
Dependent Claim
63 words
The gauge defined in claim 1, including means responsive to said temperature signal for adding to the capacitive sensor current a compensation current corresponding to the change in mass of the liquid below the bottom of the capacitive sensor resulting from changes in the temperature of said liquid, thereby to provide a gauge output signal substantially independent of the temperature of said liquid.
Claim 4
Dependent Claim
132 words
providing an output indicative of the fluid mass between said plates; B. a temperature sensor providing an electrical output indicative of the temperature of the fluid in the tank in the vicinity of the capacitive sensor; C. a source of alternating current responsive to the temperature sensor output to apply to the sensing capacitor a driving signal whose magnitude varies in inverse proportion to liquid volume changes caused by temperature changes, whereby the sensing capacitor output is maintained independent of temperature; D. means adding to the sensing capacitor output a signal corresponding to the temperature sensor output and indicative of the change in fluid mass below the sensor plates resulting from changes in temperature of said fluid, to thereby provide a gauge output signal substantially independent of the temperature of said fluid.
Claim 5
Dependent Claim
132 words
providing an output indicative of the fluid mass between said plates; B. a temperature sensor providing an electrical output indicative of the temperature of the fluid in the tank in the vicinity of the capacitive sensor; C. a source of alternating current responsive to the temperature sensor output to apply to the sensing capacitor a driving signal whose magnitude varies in inverse proportion to liquid volume changes caused by temperature changes, whereby the sensing capacitor output is maintained independent of temperature; D. means adding to the sensing capacitor output a signal corresponding to the temperature sensor output and indicative of the change in fluid mass below the sensor plates resulting from changes in temperature of said fluid, to thereby provide a gauge output signal substantially independent of the temperature of said fluid.
Claim 6
Dependent Claim
32 words
including means for passing current though said leads and thereby through said resistor and said junctions, and 3. Including means for sensing the voltage between said leads to provide said temperature signal.
Claim 7
Dependent Claim
32 words
including means for passing current though said leads and thereby through said resistor and said junctions, and 3. Including means for sensing the voltage between said leads to provide said temperature signal.
Claim 8
Dependent Claim
12 words
one or more reference junctions in series with said sensing junctions, and
Claim 9
Dependent Claim
12 words
one or more reference junctions in series with said sensing junctions, and
Claim 10
Dependent Claim
27 words
The gauge defined in claim 2 including means for subtracting from the capacitive sensor current a current corresponding to the air dielectric capacitance of the capacitive sensor.
Claim 11
Dependent Claim
20 words
a thermally sensitive resistor a. in series with said junctions, and b. in close thermal proximity to said reference junctions,
Claim 12
Dependent Claim
20 words
a thermally sensitive resistor a. in series with said junctions, and b. in close thermal proximity to said reference junctions,
Claim 13
Dependent Claim
85 words
The gauge defined in claim 1 including A. means for summing the temperature signal with a reference signal corresponding to a selected reference temperature so as to provide a compensating voltage corresponding to the difference between the mass of liquid below the bottom of the capacitive sensor and the mass at a reference temperature, and B. means for adding to the capacitive sensor current a current proportional to the compensating voltage, thereby to provide an output current substantially independent of the temperature of said liquid.
Claim 14
Dependent Claim
30 words
a pair of leads a. extending from said probe, and b. connected to opposite ends of the series combination of said resistor and said junctions, and B. a readout unit
Claim 15
Dependent Claim
30 words
a pair of leads a. extending from said probe, and b. connected to opposite ends of the series combination of said resistor and said junctions, and B. a readout unit
Claim 16
Dependent Claim
16 words
The system defined in claim 1 in which said temperature sensor comprises A. a probe including
Claim 17
Dependent Claim
25 words
A liquid mass gauge having a single capacitive sensor for indicating the mass of fluid in a tank, said gauge comprising: A. a capacitive sensor:
Claim 18
Dependent Claim
25 words
A liquid mass gauge having a single capacitive sensor for indicating the mass of fluid in a tank, said gauge comprising: A. a capacitive sensor:
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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) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |