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US4083248A
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US
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Digital liquid-level gauging systems
Assignee: Simmonds Precision Products Inc
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Filing: 1976-12-23
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Granted: 1978-04-11
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Expires: 1996-12-23
Abstract
No abstract record available.
Inventors
- 👤 Lawrence C. Maier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:15
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/26; G01F23/263; G01F23/266
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
221 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank; a variable frequency generator including timing circuitry into which the probe is connected, the capacitance of the probe determining the period of each cycle of the generator output, in which the variable frequency generator comprises an integrator forming said timing circuitry and producing a voltage output changing at a rate determined by the probe capacitance, a hysteresis switch connected to receive the integrator output and to produce said generator output switching between high and low voltage levels on the integrator output reaching predetermined high and low values, and means connecting the generator output back to form the integrator input to reverse the direction of integration on said switching of the generator output; an oscillator for generating count pulses; and an electronic counter connected to be responsive to said generator output and to receive the count pulses from the oscillator, the counter repeatedly counting said count pulses for respective lengths of time dependent on the periodicity of the generator output to produce respective accumulated counts, each of which is directly proportional to the period of the generator output and thus a proportionate measure of the level of liquid in the tank.
Claim 2
Dependent Claim
221 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank; a variable frequency generator including timing circuitry into which the probe is connected, the capacitance of the probe determining the period of each cycle of the generator output, in which the variable frequency generator comprises an integrator forming said timing circuitry and producing a voltage output changing at a rate determined by the probe capacitance, a hysteresis switch connected to receive the integrator output and to produce said generator output switching between high and low voltage levels on the integrator output reaching predetermined high and low values, and means connecting the generator output back to form the integrator input to reverse the direction of integration on said switching of the generator output; an oscillator for generating count pulses; and an electronic counter connected to be responsive to said generator output and to receive the count pulses from the oscillator, the counter repeatedly counting said count pulses for respective lengths of time dependent on the periodicity of the generator output to produce respective accumulated counts, each of which is directly proportional to the period of the generator output and thus a proportionate measure of the level of liquid in the tank.
Claim 3
Dependent Claim
87 words
A gauging system according to claim 1, comprising: memory means having a plurality of addressable memory locations each storing a respective predetermined number, and means connecting the memory means to receive each accumulated count as a memory location address code whereby the memory means outputs said predetermined stored number corresponding to the addressed location, the relationship between said accumulated counts and their corresponding predetermined numbers being such that the predetermined number output by the memory means is directly proportional to the level of liquid in the tank.
Claim 4
Dependent Claim
18 words
A gauging system according to claim 2, in which the said memory means is a programmable read-only memory.
Claim 5
Dependent Claim
28 words
A gauging system according to claim 1, which further comprises latch means, arranged to receive each accumulated count, for storing said count until receipt of the next count.
Claim 6
Dependent Claim
32 words
A gauging system according to claim 2, comprising a digital to analog converter connected to receive said predetermined number and to output an analog signal of magnitude proportional to the predetermined number.
Claim 7
Dependent Claim
80 words
A gauging system according to claim 1, in which the integrator comprises: a voltage amplifier having an input and an output between which the probe is electrically connected to provide a capacitive feedback element for the amplifier, and resistor means connected to the amplifier input and arranged to receive said generator output, the resistor means being adjustable in resistance to enable a desired integration rate to be set to correspond to the condition when the tank is empty of liquid.
Claim 8
Dependent Claim
74 words
A gauging system according to claim 6, in which the hysteresis switch comprises: a voltage comparator having an input and an output, a first resistor connected between the input and output of the comparator, and a second resistor connected between the said output of the integrator amplifier and the input of the comparator, whereby the comparator switches between high and low output states as the voltage at its input passes through a fixed level.
Claim 9
Dependent Claim
114 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank, means electrically connected to the probe and responsive to the probe capacitance to generate a signal proportional to said capacitance, memory means having a plurality of addressable memory locations each storing a respective predetermined number, and means connecting the memory means to receive said digital number as a memory location address code whereby the memory means outputs the said predetermined stored number corresponding to the addressed location, the output predetermined number bearing a predetermined relationship to the level of liquid in the tank.
Claim 10
Dependent Claim
114 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank, means electrically connected to the probe and responsive to the probe capacitance to generate a signal proportional to said capacitance, memory means having a plurality of addressable memory locations each storing a respective predetermined number, and means connecting the memory means to receive said digital number as a memory location address code whereby the memory means outputs the said predetermined stored number corresponding to the addressed location, the output predetermined number bearing a predetermined relationship to the level of liquid in the tank.
Claim 11
Dependent Claim
18 words
A gauging system according to claim 8, in which the said memory means is a programmable read-only memory.
Claim 12
Dependent Claim
137 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank, a pulse generator producing a pulse output and including timing circuitry into which the probe is connected, the capacitance of the probe determining the period of each cycle of the generator pulse output, an oscillator for generating count pulses, and an electric counter connected to receive said generator pulse output and to receive the count pulses, the counter repeatedly counting said count pulses for respective lengths of time dependent on the periodicity of the generator pulse output to produce representative accumulated counts, which are directly proportional to the period of the generator output, and thus a proportionate measure of the level of liquid in the tank
Claim 13
Dependent Claim
137 words
A digital liquid-level gauging system, comprising: a capacitive probe for insertion in a liquid storage tank and having a capacitance variable in dependence on the level of liquid in the tank, a pulse generator producing a pulse output and including timing circuitry into which the probe is connected, the capacitance of the probe determining the period of each cycle of the generator pulse output, an oscillator for generating count pulses, and an electric counter connected to receive said generator pulse output and to receive the count pulses, the counter repeatedly counting said count pulses for respective lengths of time dependent on the periodicity of the generator pulse output to produce representative accumulated counts, which are directly proportional to the period of the generator output, and thus a proportionate measure of the level of liquid in the tank
Claim 14
Dependent Claim
71 words
A gauging system according to claim 10, which further comprises: memory means having a plurality of addressable memory locations each storing a respective predetermined number, and means connecting the memory means to receive each said accumulated count as a memory location address code whereby the memory means outputs the said predetermined stored number corresponding to the addressed location, the stored numbers being indicative of the level of liquid in the tank.
References Cited (Backward Citations)
US3375716A
Cited
US3552209A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-04-10 | 1981-10-10 | 1982-04-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-04-10 | 1985-10-10 | 1986-04-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-04-10 | 1989-10-10 | 1990-04-11 | $7700.00 | Window Closed / Lapsed |