US3868846A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for converting a temperature dependent input signal to a temperature independent output signal
Assignee: Ford Motor Co
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Filing: 1973-07-02
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Granted: 1975-03-04
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Expires: 1993-07-02
Abstract
Abstract A bridge circuit for combination with a variable resistance sensor whose resistance may vary as a function of a sensed variable and also as a function of a parasitic variable such as, for example, temperature. The bridge circuit includes at least one variable resistance which varies as a function of the parasitic parameter and is relatively insensitive to the sensed parameter. The bridge circuit comprises a first leg incorporating the sensor resistor having a tap junction whose voltage varies as a function of the sensed parameter and of the parasitic parameter, a second leg including the parasitic parameter responsive resistance and having a voltage tap whose voltage varies only as a function of the parasitic parameter and a third leg interconnecting the first and second leg voltage taps and having a signal tap whose voltage varies only as a function of the sensed parameter. In a preferred embodiment, a resistance type exhaust gas sensor whose resistance varies as a function of the partial pressure of oxygen in the exhaust system of an internal combustion engine and also as a function of the temperature of the environment of the exhaust system is compensated by the circuit of the present invention to remove temperature dependency effects.
Inventors
- 👤 Toshimoto Kushida
- 👤 Eleftherios M Logothetis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:06
CPC Classifications
G; G01; G01R; G01R17/00; F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1444; F02D41/1454; F02D41/1455; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/122
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
153 words
In combination with a resistive-type exhaust gas sensor for sensing the partial pressure of the oxygen content of the gas, a circuit connected to a source of electrical energy for reducing the dependency of the output signal upon the temperature of the sensor environment comprising: first resistance means electrically in series with the sensor forming a current flow path for the source; a first reference junction being formed between the sensor and said first resistance means; a heater means operatively associated with the sensor; second resistance means electrically in series with said heater means forming a second current flow path in parallel with the first current path, a second reference junction being formed between said resistance means and said heater; and a first voltage divider means having an intermediate sensing terminal interconnecting said first and second reference junctions which is a selected fraction of the voltage differential between said first and second junctions.
Claim 2
Dependent Claim
153 words
In combination with a resistive-type exhaust gas sensor for sensing the partial pressure of the oxygen content of the gas, a circuit connected to a source of electrical energy for reducing the dependency of the output signal upon the temperature of the sensor environment comprising: first resistance means electrically in series with the sensor forming a current flow path for the source; a first reference junction being formed between the sensor and said first resistance means; a heater means operatively associated with the sensor; second resistance means electrically in series with said heater means forming a second current flow path in parallel with the first current path, a second reference junction being formed between said resistance means and said heater; and a first voltage divider means having an intermediate sensing terminal interconnecting said first and second reference junctions which is a selected fraction of the voltage differential between said first and second junctions.
Claim 3
Dependent Claim
100 words
The circuit of claim 1 including further: a second voltage divider means having an intermediate reference terminal forming a third current flow path electrically in parallel with the first and secOnd flow paths operative to form a reference voltage signal at said reference terminal; and amplifier means having a pair of input terminals, each one of which is electrically connected to one of the sensing and reference terminals, operative to produce an output signal whose magnitude and electrical sense relative to the reference terminal voltage are indicative of the difference between the reference terminal voltage and the sensing terminal voltage.
Claim 4
Dependent Claim
30 words
The circuit of claim 1 wherein said first resistance is selected to have a resistance value substantially equal to the resistance value of the sensor at the desired operating temperature.
Claim 5
Dependent Claim
31 words
The circuit of claim 3 wherein said second resistance is selected to have a resistance value substantially equal to the resistance value of said heater means at the desired operating temperature.
Claim 6
Dependent Claim
100 words
The circuit of claim 4 including further: a second voltage divider means having an intermediate reference terminal forming a third current flow path electrically in parallel with the first and second flow paths operative to form a reference voltage signal at said reference terminal; and amplifier means having a pair of input terminals, each one of which is electrically connected to one of the sensing and reference terminals, operative to produce an output signal whose magnitude and electrical sense relative to the reference terminal voltage are indicative of the difference between the reference terminal voltage and the sensing terminal voltage.
Claim 7
Dependent Claim
46 words
The circuit of claim 5 wherein first voltage divider is composed of third and fourth resistances selected so that the ratio of their resistive values is substantially equal to the ratio of the variations with temperature of the voltage appearing at said first and second junctions.
Claim 8
Dependent Claim
46 words
The circuit of claim 1 wherein first voltage divider is comprised of third and fourth resistances selected so that the ratio of their resistive values is substantially equal to the ratio of the variations with temperature of the voltage appearing at said first and second junctions.
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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) | 1978-03-03 | 1978-09-02 | 1979-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-03 | 1982-09-02 | 1983-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-03 | 1986-09-02 | 1987-03-04 | $7700.00 | Window Closed / Lapsed |