Patent US5245979A successfully refreshed from Google Patents.
US5245979A
Expired / Lapsed
US
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Oxygen sensor system with a dynamic heater malfunction detector
Assignee: Visteon Global Technologies Inc
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Filing: 1992-10-28
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Granted: 1993-09-21
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Expires: 2012-10-28
Abstract
Abstract A heated exhaust gas oxygen sensor assembly for an internal combustion engine that changes the heater status in order to detect a malfunction of the heater. The assembly includes an oxygen sensor, heater, impedance sensor, and controller. The oxygen sensor has a sensing element and a pair of output leads. The sensing element detects the relative oxygen concentration in the exhaust gas and responsively provides an oxygen level signal on the output leads. The heater physically warms the oxygen sensor. The impedance sensor is interconnected to the output leads of the oxygen sensor and measures the impedance between them. The controller first activates and then deactivates the heater. The controller also receives the impedance signals representing the impedance of the oxygen sensor when the heater is both on and off. The controller compares these two impedance levels and, if the difference between (or ratio of) these two values fails to meet a predetermined standard, the controller issues a heater malfunction signal. The malfunction signal may then alert the driver or mechanic that a heater malfunction has been detected.
Inventors
- 👤 Ross D. Pursifull
- 👤 Julie A. Konrad
- 👤 Robert W. Ridgway
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:30
CPC Classifications
F; F02; F02D; F02D41/00; F02D41/02; F02D41/14; F02D41/1438; F02D41/1493; F02D41/1495; F02D41/1494
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
145 words
A heated exhaust gas oxygen sensor assembly for an internal combustion engine comprising, in combination: an oxygen sensor, having a sensing element and a pair of output leads, for detecting oxygen with said sensing element and responsively issuing an oxygen level signal along said pair of output leads; a heater for warming said oxygen sensor; an impedance sensor, interconnected to said pair of output leads, for measuring impedance between said output leads and issuing an impedance signal; and a controller, interconnected to said heater and impedance sensor for following a heater sequence of activating said heater and then deactivating said heater and for receiving said impedance signal when said heater is both on and off, comparing said heater impedance represented by said impedance signals to determine an impedance difference, and issuing a heater malfunction signal when said impedance difference is less than a predetermined threshold.
Claim 2
Dependent Claim
145 words
A heated exhaust gas oxygen sensor assembly for an internal combustion engine comprising, in combination: an oxygen sensor, having a sensing element and a pair of output leads, for detecting oxygen with said sensing element and responsively issuing an oxygen level signal along said pair of output leads; a heater for warming said oxygen sensor; an impedance sensor, interconnected to said pair of output leads, for measuring impedance between said output leads and issuing an impedance signal; and a controller, interconnected to said heater and impedance sensor for following a heater sequence of activating said heater and then deactivating said heater and for receiving said impedance signal when said heater is both on and off, comparing said heater impedance represented by said impedance signals to determine an impedance difference, and issuing a heater malfunction signal when said impedance difference is less than a predetermined threshold.
Claim 3
Dependent Claim
31 words
An assembly as claimed in claim 1 wherein said heater sequence is comprised of: activating said heater; waiting a first predetermined interval; deactivating said heater; and waiting a second predetermined interval.
Claim 4
Dependent Claim
74 words
An assembly as claimed in claim 2 wherein said controller follows said heater sequence at least twice; wherein said controller determines a typical heater-on value corresponding to said heater impedance after said first predetermined interval and a typical heater-off value corresponding to said heater impedance after said second predetermined interval; and wherein said controller compares said heater impedance levels represented by said typical heater-on value and typical heater-off value to determine said impedance difference.
Claim 5
Dependent Claim
50 words
An assembly as claimed in claim 3 wherein said typical heater on value is substantially equal to an average of said heater impedance after said first predetermined interval; and wherein said typical heater off value is substantially equal to an average of said heater impedance after said second predetermined interval.
Claim 6
Dependent Claim
23 words
An assembly as claimed in claim 2 wherein said controller begins said heater sequence after said engine has operated for a predetermined interval.
Claim 7
Dependent Claim
26 words
An assembly as claimed in claim 5 wherein said impedance difference comprises a ratio between said impedance signals when said heater is both on and off.
Claim 8
Dependent Claim
29 words
An assembly as claimed in claim 1 further comprising an alarm, interconnected to said controller, for receiving said heater malfunction signal and responsively indicating that said heater is malfunctioning.
Claim 9
Dependent Claim
124 words
A process for determining whether a heater for an exhaust gas oxygen sensor has malfunctioned, said heater warming said oxygen sensor, and said oxygen sensor, detecting oxygen in a gas input and responsively issuing an oxygen level signal along a pair of output leads, comprising the steps of: activating said heater; waiting a first predetermined interval; measuring an impedance between said output leads of said sensor to determine a heater-on impedance; deactivating said heater; waiting a second predetermined interval; measuring an impedance between said output leads of said sensor to determine a heater-off impedance; and comparing said heater on and heater off impedances to determine an impedance difference and issuing a heater malfunction signal when said impedance difference is less than a predetermined threshold.
Claim 10
Dependent Claim
124 words
A process for determining whether a heater for an exhaust gas oxygen sensor has malfunctioned, said heater warming said oxygen sensor, and said oxygen sensor, detecting oxygen in a gas input and responsively issuing an oxygen level signal along a pair of output leads, comprising the steps of: activating said heater; waiting a first predetermined interval; measuring an impedance between said output leads of said sensor to determine a heater-on impedance; deactivating said heater; waiting a second predetermined interval; measuring an impedance between said output leads of said sensor to determine a heater-off impedance; and comparing said heater on and heater off impedances to determine an impedance difference and issuing a heater malfunction signal when said impedance difference is less than a predetermined threshold.
Claim 11
Dependent Claim
211 words
A process for determining whether a heater for an exhaust gas oxygen sensor has malfunctioned, said heater warming said oxygen sensor, and said oxygen sensor detecting oxygen in a gas input and responsively issuing an oxygen level signal along a pair of output leads, comprising the steps of: activating said heater; waiting a first predetermined interval; measuring an impedance between said output leads of said sensor to determine a first heater-on impedance; deactivating said heater, waiting a second predetermined interval; measuring an impedance between said output leads of said sensor to determine a first heater-off impedance; activating said heater; waiting said first predetermined interval; measuring an impedance between said output leads of said sensor to determine a second heater-on impedance; deactivating said heater; waiting said second predetermined interval; measuring a heater impedance between said output leads of said sensor to determine a second heater-off impedance; determining a typical heater on value corresponding to said impedance after said first predetermined intervals and a typical heater off value corresponding to said impedance after said second predetermined intervals; comparing said impedance levels represented by said typical heater on value and typical heater off values to determine an impedance difference; and issuing a heater malfunction signal when said difference is less than a predetermined threshold.
Claim 12
Dependent Claim
211 words
A process for determining whether a heater for an exhaust gas oxygen sensor has malfunctioned, said heater warming said oxygen sensor, and said oxygen sensor detecting oxygen in a gas input and responsively issuing an oxygen level signal along a pair of output leads, comprising the steps of: activating said heater; waiting a first predetermined interval; measuring an impedance between said output leads of said sensor to determine a first heater-on impedance; deactivating said heater, waiting a second predetermined interval; measuring an impedance between said output leads of said sensor to determine a first heater-off impedance; activating said heater; waiting said first predetermined interval; measuring an impedance between said output leads of said sensor to determine a second heater-on impedance; deactivating said heater; waiting said second predetermined interval; measuring a heater impedance between said output leads of said sensor to determine a second heater-off impedance; determining a typical heater on value corresponding to said impedance after said first predetermined intervals and a typical heater off value corresponding to said impedance after said second predetermined intervals; comparing said impedance levels represented by said typical heater on value and typical heater off values to determine an impedance difference; and issuing a heater malfunction signal when said difference is less than a predetermined threshold.
Claim 13
Dependent Claim
62 words
A process as claimed in claim 9 wherein said step of determining a typical heater on value comprises the step of determining an average of said impedance after said first predetermined period of time; and wherein said step of determining said typical heater off value comprises the step of determining an average of said impedance after said second predetermined period of time.
Claim 14
Dependent Claim
32 words
A process as claimed in claim 10 further comprising the steps of detecting that said engine has begun operation and waiting a predetermined interval before said step of activating said heater initially.
Claim 15
Dependent Claim
26 words
A process as claimed in claim 11 wherein said impedance difference comprises a ratio between said impedance signals when said heater is both on and off.
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